Everything is great about the GXP.... except the general reliability. I wanted to get one 5 years ago until I read up on the problems, and the bills associated with fixing them. Also hard to find good tech's for that engine as well because you pop the hood and they all go: Wut.
Other problems to look out for:
Water crossover gaskets and waterpump problems
Oil and coolant leak prone
Shitty rotors
Gas mileage 22 on the highway, and 16 around town (real world numbers).
I'd get a SSEI before a GXP, but I will say the GXP looks sweet and has lots of gizmos, and hard to beat that V8 rumble. Although I've read some people who have had GXP's with no problems at all (except be prepared to spend money at the pump) and love their cars. So could be a crapshoot.