It is a pretty tough race, but very well supported. It starts off with mostly roads/ double track, but it does go into quite a bit of harder and some technical single track as you are approaching the 30 mile mark. So it actually gets harder as you get more tired! There is a lot of climbing with some significant grades, as well as technical up and downhill. It starts and ends at the Ascutney Ski area-
Everyone I know has had a great time at the race (maybe not the year that it was pouring rain and very very few actually finished)- but the same people will tell you that it is TOUGH and not to underestimate it.
Here are some picts:
http://www.skipix.com/vt_50_mile_05/time_list.htm
http://www.flickr.com/groups/vermont50/
And a race report from '06
http://www.visionmtb.com/forumvb/showthread.php?t=10774
The best rides are the ones where you bite off much more than you can chew--and live through it.