If you want some more credible opinions from American drivers I'd suggest reading these two articles:
2011 Regal Second Drive: Car and Driver
2011 Buick Regal Third Drive (On American Soil): Autoblog
* The Autoblog post goes into far more depth than the C/D article
Generally speaking, its what you'd expect for a German-engineered (and built), entry-level luxury sedan. Its quiet, refined, and has a few more sporting credentials than your regular choices from Honda, Toyota and so on. But, this car is shooting straight for the Volkswagen Passat, Acura TSX and to some extent the Lexus ES350. The Buick will win on content for money, and I'd be willing to bet that, aside from the Acura, it will most likely be the best to drive sportilly as you please.
So, getting back to the question:
Would you buy one?
Probably, but it depends on a few things. First of all, the engine package decides a lot of this. While the 2.4L DIG would be more than enough to keep most people happy, I'd need the 2.0L Turbo to keep the juices flowing. As soon as that is equipped, with all of the goodies that come with it, the price starts to go up quickly. Considering that the basic CXL starts at $27K, you're in a pretty wide field there. Bump up to the Turbo CXL, and you're about to cross the $30K threshold. Then things get really interesting.
Having only seen and sat in one for mere moments, I can't make a fair call without driving one. This is probably the first time in a long time that I really, really would honestly want to own a Buick, so that has to say something. But to make it be enough to entirely forget about my general preference toward Volkswagen, that will have to be seen.
TL;DR - Make it a CXL Turbo and I'd have it over most of the cars in its class, but its the lower-priced competition that might take my attention away.