I just thought I'd give some positive feedback.
Speed with debugging turned off: terrific. I'm not doing any benchmarking here. This is just my overall impression doing development work within VMs. Apps load quickly. I never see any jitter.
(Other than the need to hack the config file) I'm pleased that I can run a WinXP guest VM full-screen on a 30" Cinema Display. Sweet stuff.
Working with USB flash drives seems a lot faster. Detection and mounting, read/write, and unmounting is quick as lightning now.
I don't see as much disk thrashing. I can move between a VM and OS X without much (or any) delay.
I was skeptical about VM packages, but I love them now, partially because (in combination with the new "VM Library" screen, I have a short, easy-to-understand list of VMs. That counts for a LOT.
Anyhow, with all the "fun" tackling bugs &c. on a daily basis, I thought I'd give some positive feedback for the great improvements in Fusion.