Macworld published a long and focused review of new Parallels Desktop 3.0, providing following pros:
Many substantial new features; 3-D accelerated graphics support; Snapshots and Undo Disks features allow you to easily revert a system to its previous state; support for Boot Camp partitions as virtual machines; Explorer program facilitates easy transfer of files between operating systems.
3-D graphics support still has some problems; Shared Application support may be overkill in some situations; tech support still somewhat complicated.
and bottom line:
Parallels Desktop 3.0 is currently the best solution for running Windows, Linux, or any of many other operating systems alongside OS X. With the inclusion of (still limited) 3-D graphics support, Snapshots and Undo Disks, virtual appliances, and many other features, it’s a compelling alternative to rebooting via Boot Camp. Tech support has improved, although you will pay somewhat dearly if you need an answer via phone. Unless you need full 3-D graphics support, or support for some esoteric hardware, Parallels will probably get the job done for you.
Read the whole review at source.