REAL MEN RIDE SINGLESPEEDS I've used the product since the early days and I'm now on version 3.0 on a 2.1ghz Core Duo / 1 gig ram. I'm an occasional user as I sometimes need to run Windows applications to work with MS databases. I think these guys did a great job in leading the way for us Mac users to free ourselves from the throbbing fans and ugly unreliable world that is PC hardware. The product is easy enough to use and does the job. I haven't suffered compatability issues and moving files from OSX to Windows has worked flawlessly.
However, you need extreme patience as the application can take an age to load and in the process will bring your Mac to a crawl. When its loaded it runs okay, but switching back to the Mac desktop you need to learn patience. Perhaps, I've been unfortunate, but I've also suffered serious unrecoverable system crashes. So, I'd recommend ensuring Time Machine is up to date and that you have a bootable image somewhere (I recommend SuperDuper for this) - just in case.
The performance issues and occasional crash might just be down to local issues with my machine (which has been rock solid outside of using Parallels) or some configuration problem.
Overall, I'd recommend this product and I'll continue to use it but alongside with my 1 tb backup disk.
(Version 3.0.5626)