I think the deciding factor will be how fast and smoothly it runs.
I have a cingular 8125 (HTC wizard), and loading up TomTom takes over a minute which I find absurd. WM5 can just be really slow. Loading text messages takes about 5-15 seconds.
I want lightning fast response to what I'm doing and lets face it, the browsers on all WM5 are crippled as hell. The ONLY time I use them is if I absolutely HAVE to look something up. The zoom feature on these opens up a whole new conveinience factor.
Playing MP3's via TCMP or WMP? Forget it. I have a pair of bluetooth headphones and using them sucks up so much CPU usage on the phone that it becomes just about unusable. Not to mention the lack of headphone jacks. Adapter? Yeah, OK, if I want a 2 inch hunk of plastic sticking off of this thing maybe. Movies? Ehhhh, Maybe. Storage on a WM5 unit? Max of 4GB + internal ram. That will run you another $75 for the mini SD card anyways.
I have no use for corporate email, so I have no comment or concern regarding that.
I've wanted to replace my old, dead iPod for awhile now but I don't want to carry around a phone and iPod and I don't want to have to shell out another x amount of dollars for a bluetooth adapter for my iPod.
So, I put this in perspective for myself.
iPod - $250
Adapter for iPod - ~$50
My current phone cost me - $300 + $40 for the MiniSD
Total: $640
So I ask myself, why would I not shell out $599 to get an iPod, a damn good looking browser and a phone that looks like it works damn well?