in general I think it is worth it if the blu ray library has or will have material that you're interested in.

I run an HD DVD player (still) to my 720p Pioneer and for many films, the picture is simply fantastic. But certain transfers to HD DVD (which is lb for lb equal in video quality) did not impress. My copy of "The Perfect Storm" did not look so great and I'd venture to say that a good upconverted DVD of the same movie would have looked almost identical.

However, Blade Runner, a much older movie, never looked so good

I'll eventually go BR, although I'm still licking my wounds from being on the wrong side of the format war. I think the Oppo BDP will be my pick because of its versatility.