It would be interesting to have "qualified" beta testers. Of course qualify can be a slippery term. However, overcoming that, it would be nice to have some sort of bug tracking system that people could put real, reproducible bugs into that the Parallels team can check and fix.
Having worked in hardware design and software testing, the larger the test base the more bugs show up, and can also be addressed. However there are priorities on which bugs are fixed when etc.
Whats important to me, isn't necessarily important to someone else.
Overall my I have been satisfied with parallels, it works for me, on those one or two apps that I need to run under windows. But thats my need - run the oddball program(s) under windows.
Other folks are looking to run full VM OS for some other need, perhaps production environment, other testing requirements etc. Thats their need, whether I agree with it or not.
People running beta really really need to understand (and its obvious they don't) what that means and what you get. For me, its been great, and I have a backup image, just in case. I also don't jump on the newest beta, let some one else lose their image, system etc and have problems.