Depends on its condition!
At 24 years old how good a bike is is much more a function of how its been looked after than its original features, so its hard to give much meaningful advice. I had a DR600 for awhile about 8 years ago and remember it as a very good solid bike with no issues - I certainly don't remember vibration being worse (or better) than any of the other large singles. If you are interested in it the only way to find out what it's like is to take it for an extended ride and decide if its for you. Likewise with the price you quote could be good value if it is sound - equally it might easily be worth virtually nothing (however cosmetically perfect it is) if it needs engine work, tyres, chains, brakes etc..
Sorry I can't give you any more specific advice - older bikes are definately a case of "buyer beware". Having said that, there are plenty of bargains out there - a lot of people seem to think any bike more than 10 years old or with more than 50,000km on the clock is worn out whereas if they have had a caring owner this is far from the truth. I buy all my bikes at about that age / mileage and then typically put another 50,000 km on them in two years before changing them again - and with the exception of a certain non-Japanese brand (OK it was BMW - twice) never had any serious problems or breakdowns that couldn't be fixed at the side of the road.