That's a big bike for a first timer. If you can be patient to learn the rhythm of starting this beast, it is well worth it. I'm 5'-7" and have a 98 WR400. When I first started riding it, I fell over a lot on the trails by being in the wrong position when I stopped.
I lowered the forks on the triple T's about 3/4" and shaved most of the foam off the seat, and now it is no longer a problem.
Leverage is the key to controlling this bike, and you have to get it closer to the ground if you are going to enjoy it.
Also, if you want to spend $200, mountainsports.com sells a lowering link for the rear shock. I didn't need it, but I've heard this also helps a ton. The price for that bike sounds pretty good. If he took care of it, you will happy with your investment.