I've owned a few different Land Rovers over the years, with my current vehicle being a 95 Discovery. I've always loved the D90s (my first rover was an AAYellow D90 soft top), and think that they're amazingly capable. But I would caution your friend about a couple of things before he picks up a 90.
1. I think they're somewhat over priced. Since they were imported for only a few years in the mid 90's, people tend to ask silly money for 10 year old vehicles. There are bargains to be had, but he should definitely shop around.
2. They're probably one of the most capable factory vehicles ever made. A lot of fun to wheel and fairly easy to modify. But, the NAS trucks live and die by their service schedules, which are pretty rigorous for a typical vehicle. Almost every time my truck broken, it was because of something that was past its service interval and I meant to get to it eventually. Keep up with it, and it'll be a reliable workhorse
3. Don't know where your friend lives, but the factory soft top sucks. Usually by the time its cold enough to put the top on, its shrunk to the point that it's a major battle to put it on. Don't know why they're so difficult, since they're made by Besttop who makes a decent top for the Jeep Wranglers. When you do get the top on, there are usually sizeable gaps between doors and the top etc. Not that bad if you live in an area where the temperatures are mild or predictable, but here in CO it can be a huge pain (not uncommon to have snow fall and temps in the 70s or 80s in the same month). On the other hand, the hard top is a pretty decent vehicle to go with.
When it came down to it, I figured a Discovery would meet my needs better since its lockable, has more load carrying capacity, greater cruising range, and is more comfortable. But I still think frequently about what a fun truck the 90 was....
I'm not trying to talk your friend out of the truck, it's just that I'd like for them to go in eyes wide open. It takes a certain personality to tolerate a Land Rover. ;-)
my 2 cents (and a little more)