You can get at least the same, if not better, quality out of a HTPC. Perfect results do however require some setting up, fine tuning, and alot of patience.
For alot of people thats part of the fun, well, at least for me.
I don't know the exact specs of the Oppo, but there are good standalone BluRay players out there, and if your only goal is to watch disc based media like BluRay or DVD, then i would say go for it.
HTPCs are really alot stronger when it comes to file-based media from the internet, for discs-only you should be fine with a stand-alone.