If you think that's bad, you should try Sonic Adventure 2. But facts are facts, this is an alpha version (not even beta yet), so exxpect graphic problems to be normal until future releases fix them. Just give the authors some time, they intend to get all these little bugs worked out.
I've seen 3 posts in the last 4 months concerning gfx problems with Virtua Athlete, so trust me, you aren't alone . But if the alpha version is already running as good as it is, it's a pretty good indication that the final version will be 100% compatible.