I have a '96 and it's been good. I put OME 2" springs in the rear and cranked the torsion bars in the front to get a little lift, I think if I went with a little larger tire it would have been a little more capable (285 vs 265). I added a 3rd row so I can haul a squad of girls, added rails, OME front bumper, and a real rear bumper.
As for what I've done to it, mine has about 214k miles on it, when I got it I drained all the fluids and I don't know if the previous owner had touched them (the rear looked like it had some water in the fluid). I replaced plugs and filters, replaced wheel bearings, and replaced the U-joints. I broke my tie rod on a trip to Moab and I believe I also lost a CV shaft around the same time (one may have caused the other). I used some ES150R and ES150L joints and had Carl thread some tube for my tie rods and I don't believe I will have an issue with them in the future, the CV shaft was just replaced using an Oreilly part.
I think part of the resale value equation is Isuzu has left the US market so no dealer support, the wrecking yards seem to have plenty of them so parts are available if you go that route, it wasn't a concern to me because I don't go to dealers for support. Other random thoughts, the rear axle is beefy probably somewhere between a dana 60 and a 44, however there aren't any available ring/pinon options available if you want to change from the stock 4.56 gears. For parts spares I would invest in a CV shaft (both sides are the same) and replacement/upgraded tie rod.
