I bought tickets for 310, row 10 for the Patriots-Indianapoli s Colts game back in 2010. Amazing seats. The 50 yard line will have the best line of sight on the top level but I hear the corners aren't so bad either.
The seats were just as comfortable as the seats on the first two levels of seating. There is no way you can go wrong with these seats.

You can easily go wrong with parking though. If you decide to cough up the $40 it costs to park, then be prepared for a two hour wait exiting the parking lot to go home. If you're able to access the stadium via public transportation of some type or are staying at the nearby Renaissance, then do so. I would avoid driving to Gillette Stadium at all costs unless you're a big tailgater with tons of free time on your hands.