I installed Parallels 4.0 on the iMac last week, upgraded my licenses and converted my bootable images to the new format. It took a while to do as the conversion process takes a long time. While the installation was trivial, I had 4 different bootable images to convert, which took a good 3 hours to migrate even though they were only a couple of gigabytes a piece and only have a handful of applications installed. But I had no problems and everything worked fine. There are a couple subtle changes to the interface that make management of the images a little easier. I have not witnessed the performance enhancements that are claimed to be present, but I have not had performance issues in the past, so your mileage may vary.
As the build I used was the one provided right after the official announcement, I was expecting that a new one would be released soon to clear up some small issues that have popped up. Sure enough, build 4.0.3540.209168 popped up today. Problem is I cannot install it. The ‘Continue’ button is grayed out; tried a couple of times, but there are really no options other than to accept and continue, but still I cannot proceed. I cannot imagine something this simple not getting picked up by QA. Anyone else out there having this issue?