the battery grip helps a lot...I agree......
What kind of problems?
I think you saw my post on the backfocus issue and it is horrible when shooting wide open. (major misfocus)
the other problem is definatly a touch of under exposure...I keep my EC at +1/3 sometimes +2/3
I can rarely get any results when shooting at F/2.8 or less which makes my 50mm f/1.4 almost pointless...it is however insanely sharp at F/7.1

I now have my Canon Rebel XTi w/ a Canon EF-S 17-85mm f/4-5.6 IS USM lens! I'm charging the battery right now and once I read up on it, I'll post some pictures...
