You will be impressed
I drove a 2002 Trooper for nearly 8 years and well over 100,000 miles. I didn't really want it when I bought it and dreamed of owning a Tacoma the whole time I owned it, but now that I have sold it I am kicking myself.
I bought my Trooper because it was the cheapest newer 4 door SUV I could find with real offroad parts- 2 speed case, decent ground clearance, etc. I bought mine when it was 6 months old with 15k on the clock for 50% of the sticker price.
I couldn't stand the ride so based on some internet chatter I purchased a basic OME suspension (medium load)- just coils and shocks. I flipped the ball joints, cranked the torsion bars and had it aligned. Night and day difference! Stock the ride was wallowy and unresponsive. With the OME it was tight and not jarring- the only way to go and it didn't cost too much more than just new shocks.
I put 10 ply Yoko AT's (285/75/16) on it and drove the wheels off it. With just those basic mods I was able to wheel all over the place- to the point that I sold my ATV. I built a very basic cargo deck for the rear and with the rear seats folded down I could sleep comfortably (I am 6'1"+).
Maintenance wise I always checked the oil every 1,000 miles. While the 2002 may have been better on oil I still had to add a quart every 1,500 or so miles. I did all of the recommended maintenance and never had any real issues. The transmissions have some quirks, but I found a local guy who knew them really well and just had the fluid changed annually. In the last year I racked up quite a few bills fixing small stuff O2 sensors, fuel pump, etc, but most of that was due to me crossing a pretty deep river. Note- they will ford 36" rivers just fine, but suck water @ 40".
After talking bad about mine for 8 years I am looking to buy another after having sold it two months ago. The car was awesome and never let me down. BTW I sold mine with lots of new maintenance parts for $4,200 and just saw a really clean 2002 w/86k on CL for $5,500.
For parts you need to talk to Jerry Lemond on Planet Isuzu- he is awesome!