I own a Grand Cherokee, and my big disappointment with the regular Cherokee (apart from silly styling elements) is that its a front-drive platform with a limited 4x4 capability scabbed on, just like the current Explorer, the new Blazer, and far too many modern compact SUVs. Actually its a little better than those in that the Explorer is really JUST FWD with an on-demand connection to the rear axle ONLY when front-wheel slip is detected, but the Cherokee is still FWD at its core. The Grand Cherokee is still a real rear-drive based 4x4 with an honest-to-god locking transfer case in 4-low range, although electronic intervention with the ABS does what would be done by limited slip or locking diffs in an old-school Jeep.
As far as reliability, the first couple years were problematic with the 9-speed ZF transaxle, but I'm not hearing much about that anymore. The Pentastar v6 is bulletproof, I know very little about the Tigershark but again, NOT hearing bad things is generally good. A quick glance at some Jeep forums seems to indicate most people are generally happy with it.