The front end needs some work - I currently have a bad front right wheel bearing, a worn front right axle and a slight leak in my differential oil seal. This is all related, and not really a difficult fix, but the dealer quoted me an exorbitant rate to have them do it.
The ABS system no longer functions. Again, probably something simple, but as the ABS system is not intended to be user-serviceable, I took it to the dealer so they could read off the codes and they want to basically replace the entire system at a cost of $2,700. So I'm just living without ABS - it's not strictly necessary. In fact, I've never owned a car that had it before - this would have been the first.
From the previous owner's service records, it looks like he previously had the front axles replaced as well, along with some leaks being plugged around the seals in the transfer case and differentials. These seem to be common issues in this model and year.
I'm a fairly new owner of this vehicle and despite its issues, I still love it. It's a great balance between on-road comfort and real off-road toughness. I don't feel like a pretender in this car. My Jeep has obviously been driven hard, and that's common even for Grand Cherokee owners - these things were built as real 4X4's, not as some sort of glorified minivan. At the same time, though, you're not giving up anything in comfort or features. My Limited's got leather seats, a sunroof, all power, etc.
The two nice things about Jeeps are a) there is a large online community of Jeep owners, most of whom are very helpful and will be glad to teach you to do many of the most common maintenance and repair jobs, and b) these vehicles are very easy to work on. Most of my front-end work that my dealer quoted me over $2,000 to perform I'm now planning to do myself. I've actually seen video of the process and there's really nothing to it. Replacing an axle and a wheel bearing is not something I ever thought I'd be doing, but it is literally just a question of unfastening a few bolts and pulling the whole thing out. Parts are available at any auto parts store. Except for the ABS system, this entire vehicle was meant to be serviced by the owner. Even the owner's manual itself talks about maintenance of the differentials and transfer case - they expect you to be under there working on the car yourself.
Obviously there are things I can't fix myself, and if my engine or transmission ever blows up, the car's probably toast. But the 4.0 engine is legendary for reliability, and it's a strong engine - I never feel a lack of power. No oil consumption either. My trans seems fine so far but it's probably the one thing I really worry about long-term - it does whine in reverse when it's cold, even after changing the fluid and filter.
These are probably not the right cars for you if you're neither mechanically inclined (or willing to learn) nor interested in a real 4X4. I wanted one because of the harsh winters we have where I live; I didn't know how easy they were to work on until after I'd bought mine. But now I realize why there are so many old Jeeps still on the road in my area - long after most cars would no longer be cost-effective to maintain, you can buy cheap parts for any older Jeep and install them yourself very easily.