The biggest thing I see though as a complaint is sticking to 5400rpm harddrives, which will still be a bottleneck. I think they should have went with higher capacity 7200rpm harddrives as the baseline. Some people were expecting SSDs to start, but of course still too early for that to become de facto. Over $1000 and getting a 5400rpm drive is disappointing no matter who you are.
Processor upgrades are good, though they're just meeting standards on the 13" (u36jc from Asus has already been sporting an i5, except faster than the base model) while the quad cores on the 15 inch are a pretty big step up, though a dual-core model should have been an option.
Graphics: I find the switch to AMD/ATI interesting. Benchmarks still need to be determined, since apple just used portal and hl2e2 as relative benchmarks is incredibly uncertain, we dont know what graphics settings they mean and such. Still, its inbetween a standard and gaming-focused gpu, though not enough to really help OS X as a gaming platform.
Battery life took a hit, and is no longer really a big point. Quite a few windows laptops up in that 7 hour cap (which even then may still be exaggerated, once again more testing needed).
Thunderbolt... eh, largely irrelevant. Performance is largely going to be equal to USB 3.0 because there aren't many uses yet (4.8gb/s is like being able to use a fast SSD externally, and that isn't anywhere near practical yet). Since it isn't USB 3.0 though, it might suffer from lack of general interests, unless it starts getting adopted more from PCs (which will sort of make this neutral anyways).
Overall the new line isn't really too impressive. In my opinion it still remains overpriced, though some of the new capabilities due to sandy bridge (such as faster processors or a 2.0ghz quad core in a 15 inch) are nice, but definitely let the PC market flesh out with sandy bridge before making any decisions.
As for direct, immediate PC competitors, I still think the U36JC is on top of the 13 inch macbook, though it lacks an optical drive (though that probably isn't really a huge dealbreaker anymore, they're becoming more irrelevant). I think the biggest challenger will be Lenovo's new laptops or Asus when they update the U-series.