Just completed the campaign on this, thoughts below:
+Graphically impressive, in particular the lighting (sun glare etc)
+Performance isn't too bad, 60-100fps on my GTX470
+Some exhilarating set pieces, in particular in the rockies having to avoid avalanches, or swerving to avoid enemy helicopter spotlights and gunfire. As a pure racing game it isn't anything special but those sections really add to the game.
-Incredibly shoddy port on the controls front, the game features some 'simon says' scenes where you have to press certain keys within a timelimit, unfortunately it just puts up an Xbox button on screen so you have to try and guess what button that might be on your PC controls
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. Basically I just had to keep repeating those sections many times gradually figuring out which button was which. Totally unacceptable in this day and age, why couldn't it say "Accelerate" instead of "B" or ideally put up whether button you have mapped?
-AI catchup (both ways) that basically means in long races there is little point dropping the hammer early doors, the final race in particular has a couple of mid-race cutscenes so there is no point building up a 9s lead as the rival will just catch you up
-Quite a short game (campaign at least), I clocked in around 2hr15min of racing which probably translates as around 3.5-4hrs of gameplay taking into account resets, restarts, cutscenes, garages, menus etc
-Don't really get to experience many cars, the only ones I drove were M3 GTS, Gallardo, GTR, R8, 918 and Huayra
-Car performance stats could be better; the 0-60 time is meaningless given every race has a rolling start, something like 100-180mph would be much more helpful
-No tuning - feels like they missed a trick here, would have been nice to be able to win/buy mods and then apply them when you reach major cities
-Game bigs up the fact you are driving ~3000 miles across America but the reality is you only actually drive around ~310 or something like that, which is nothing compared to say TDU.
Overall I didn't think it was as bad as the above bullets may suggest, but I'd say it is one of the weakest of the NFS series. One other positive is that my PC handled Frostbite 2 engine better than I expected, so maybe BF3 is more viable than I thought.
Finally just as a headsup, the 30fps limit has been removed by a patch (I held off getting the game until this was resolved).