I have not owned an H3, but did drive a rental for two weeks on Kauai last year.
It is a funky SUV that has character, decent room for its size, is solidly built, and did well on the beach, negotiating muddy rutted tracks, and driving below 50mph. Very manueverable and comfortable.
The bad: 5-cylinder engine is fine for offroad and below 50mph, but is anemic on the highway. Good for a small island, but not the open highway. At speeds over 60, I constantly had to correct its line.
On bumpy dirt-roads, the rear-end was constantly coming around. The worst I have ever experienced. I had to drive seriously slow to keep the rear in-line with the front, as while the kids thought it was good fun, the wife put the kabash on the tail out antics. I drove the same roads in a Suburban and Exploder with no such issues. Of course, I did not take these two on the sand and over the muddy track, where the H3 redeemed itself.
As I'm sure you know, the H3 is not being built anymore, so I would worry about resale. Parts should be OK, because they are mostly shared GM.