I've not had any problems with ANY of Parallels betas. I use them pretty rigorously and I've found it's more stable then my native PC at work. This version has worked as well. A few things obsessive things I do with each upgrade.

1. Shut down and back up your Disc image
2. Uninstall previous version of Parallels
3. Install newest version
4. Boot up your Disc image and leave it alone. Parallels will AUTOMATICALLY install the Parallels tools
5. Repair permissions (which by the way never yields any issues with Parallels...Adobe is another issue)

This version seems great so far and unlike VMWare Fusion does not have a noticeable GUI lag. I've purchased both products so I'll keep testing both of them. Will see how the final products compare