Awesome cars in my book, but I'm a bit biased.
Watch out for the typical issues, strut rub (stock 17s), fuel line rubbing, door locks, and a few other commons issues.
Pull the GM VIS before purchasing, see what's been done to it, make sure the issues have been corrected. If you looked at my VIS you'd be terrified and run from my car, but I'm absolutely anal about it and every single thing that is a touch off has been addressed and corrected to my liking (which took more than once a few times).
Nothing wrong with a LS1's, everyone praises the LS2s and says they are much faster. Faster, yes...much, no. When I got mine (Jan '07) there was still a hefty price difference between the 04's and 05-06's, and the extra coin wasn't worth shelling out, particularly in the 04 only color combo I have.
If there's anything you want to know or check out let me know. I obviously have an 04, my room mate has an 06, my dad had an 06, and I've got 4-5 good friends with them too. To say I know a little something about these cars is an understatement.
I'm sure the few others with them on here will chime in soon..