RUN!
The Range Rover P38 was touted as the most advanced truck Land Rover had ever made at that time (1995-2002). The most features, the most options, and the most electronics. As they get older a host of things go wrong. They share virtually nothing with anything else in the LR range and parts and labor are stupid expensive, hence the low resale value. I would steer clear of one of those especially if it is to be your first foray into Land Roverdom.
I like them, but I wouldn't own one.
EDIT:
Pros, it's like driving your comfy living room around. It is still a reasonably good off road vehicle but only after you take out the problematic air bag suspension and replace it with springs.
Cons, cost of any part for it. Which, with that many miles will need replacing. Few places make aftermarket parts for them (armor, bumpers, etc.) and the places that do charge a hefty premium. Plagued by electrical gremlins.
IMO the cons out weigh the pros with the P38. It really does take a special kind of person to own, wheel, and maintain one of those.
MPG:
Highway, bad (16)
City, worse (12)
Combined, terrible (13)