Some interesting comments here I must say - for what it is worth, I'll chip in as well.
I definitely agree that, on paper at least, Red Bull look like the clear favourites, especially when their car is placed in the hands of Vettel - Newey has indicated that the new car will be an evolution of the RB7 (which is part of a string of successful cars), and although a number of changes have been made to the regulations that are likely to cut into their advantage (not just diffuser blowing, but also restrictions on engine maps, clutch control and small changes to the aero tests), the team have matured considerably and Newey is quite inventive. The only weak spot, though, is their management of driver strategies; their inherent speed advantage has saved them a number of times, but if the field were closer to them then you suspect that Red Bull might well have thrown away a few easy wins through careless decisions. Assuming that the field does close up on them a little next year, I suspect that Red Bull, though they've improved in that area, might well still find themselves throwing away points with poor decisions, and in a tighter championship that could cost them dearly.
McLaren, you have to assume, will be reasonably competitive, provided they can overcome their recent trend of a slightly weak start to the season and having to develop their way into the frame. I wouldn't be surprised if the team does have something slightly unusual up its sleeve next year, albeit a little less radical than some of their more recent inventions, and both drivers look like they will be strong performers next year (Button has been driving superbly last year whilst Hamilton seems to be overcoming his personal issues); whether they can maximise that potential is another matter.
Ferrari are possibly one of the bigger conundrums for this season - the rumours that have been coming forth from Piola recently are very interesting, and suggest that Ferrari have actually delivered on their promise of a much more radical car for 2012 (there is talk of major changes to the suspension layout, sidepod configuration, cooling systems and modifications to the floor). If they do manage to deliver, Alonso may well prove to be the strongest competitor for the title this year - hell, last year he managed to take podium finishes at places like Suzuka in a car that hadn't been developed since Hungary, and if the car is close enough Alonso could well be the victor this year. It's certainly the case that the recent rule changes are going to help Ferrari the most since they had a quite strong car last year despite not using the EBD extensively.
As for Massa, this is going to be a critical year for him - Domenicali has made it clear that Massa is driving for his career next year as the team are running out of patience, especially off the back of a fairly lacklustre 2011 (even allowing for Hamilton running into him on multiple occasions, Massa was at one point under threat from Rosberg in the WDC last year when frankly Massa should have been much further ahead of Rosberg).
Mercedes are probably going to be closer to the rest, but given their slightly more limited budget compared to the above three it is hard to see them making significant in roads. If the top teams slip up at any point they might sneak the occasional podium finish, and like Ferrari the rule changes should play to their advantage, but it's hard to see much changing nevertheless. As for the drivers, it'll probably be similar to this year; Rosberg being the better in qualifying but Schumacher making some of that back on strategy and race craft, with the difference between the drivers narrowing.
Depending on how much effort Lotus put into their ride height adjustment mechanism, their performance this year could oscillate quite a bit; the defection of a number of their designers to other teams is likely to hurt their development progress. It might well be another case of the team starting out fairly well, only to slide back down the grid as the cars are developed; if so, we might see Kimi becoming increasingly frustrated as the season goes on. As for Grosjean, I expect that he'll put in a better performance this year compared to his first attempt, but it may take him some time to settle in before he starts performing at his best.
Force India have some pretty aggressive targets this year, whilst the cash injection from Sahara seems to be resulting in an expansion of their facilities (they are thought to be working on a new wind tunnel at the moment, although they are waiting on planning permission). Di Resta seems to have calmed his driving down a little after a slightly ragged performance, whilst Hulkenberg will be eager to prove that Williams made a mistake in sacking him; overall, Force India does have enough potential for them to pressurise Lotus and Mercedes I reckon, though the inexperience of their drivers might mean that they aren't able to do that on a regular basis.
Sauber will probably have another fairly steady season this year given that there have been few changes to the team in the past 12 months; probably behind Force India more often than not, but probably ahead of Toro Rosso more often than not. Perez will be hoping to build on the solid performances he put in during 2011, perhaps with an eye on Massa's seat at Ferrari if things go well, whilst Kobayashi should hopefully be given more flexibility on his strategies and not hamstrung by being forced to stay out for so long.
I kind of expect Toro Rosso to fall back this year, like most posters; Ricciardo drove well on the whole last year, but in a much more competitive environment he could find things tougher, whilst Vergne's inexperience could see him making a few silly mistakes in the earlier part of the season. The influence of Red Bull - especially Marko and to a lesser extent Horner - could also be disruptive, given that Horner has already talked about how he wants to see the two drivers fighting each other; that doesn't sound like a particularly good recipe for strong inter team relationships. Red Bull are also thought to have helped themselves to a number of Toro Rosso's more skilled staff in recent years; that sort of policy may well start hurting the team in the longer term, especially if Red Bull keep on concentrating their resources and investment on the main team.
Sadly, I can't see Williams doing a great deal better this season - yes, the team have finally made the changes to their technical staff that they should have a number of years ago, and they have learned a lot from their mistakes this year, but it is a lot easier to fall back down the grid than to make your way back up it, especially given the changes and investment other teams have made in recent years. Hopefully Maldonado might not be quite so hot headed as he was on occasion in 2011, Bruno Senna may prove to be a blessing in disguise and the deal with Renault should lead to some improvements, but there are far too many fearing a slide and collapse rather reminiscent of the original Team Lotus or Tyrrell teams.
Caterham have a number of promising aspects for 2012 - the changes in regulations should bring them closer to the pack, their budget looks increasingly robust with sponsors flocking to their team and Heikki is performing very well (even if, somewhat ironically, it was Trulli who finished ahead of Heikki in the standings last year). The team probably will still be towards the tail end of the midfield next year, and more often than not out in the first part of qualifying, but occasional trips into Q2 on merit are possible; reliability has to be improved, though, because all their hard work could be undone if HRT or Marussia get a fluke high finish in a race of attrition. As for points, Caterham might be in a position to get close to the points occasionally but could come up just short (though I wouldn't mind being proved wrong on this prediction).
HRT are likely to treat 2012 as just another year they need to survive through, to be honest - the restructuring of the team has come at a particularly awkward time, the team hasn't really been able to invest all that much as loan repayments to Banco Popular and Carabantes seem to have swallowed up most of their budget last year, and they are still searching for a permanent base following the departure of Kolles and his staff (which also seems to suggest the team will have a shortage of designers to develop their car).
As for Marussia, I expect that 2012 may offer a small improvement but nothing too surprising. Symonds has revealed that their 2012 car is relatively conservative since the team want a reliable, solid car that they can clock up as much mileage on in pre-season testing as possible, so although it is likely to be fairly different to the MVR-02 it probably won't be especially striking or quick, but probably more reliable if nothing else. Glock is probably going to be fairly quiet as a result, and somewhat wasted on the team, whilst Pic may well make as much of an impression as the last two pay drivers the team has employed in the past; I suspect, though, that the team may well be ahead of HRT simply because they have suffered from less disruption in recent months.
Martin Brundle, on watching a replay of Grosjean spinning:
"The problem with Grosjean is that he want to take a look back at the corner he's just exited"