Well, you can only sync one gmail account (without buying an app which allows more) so having multiple gmail accounts means I had to forward one of my emails to a hotmail account and haven't been able to sync my other google calendar with my handset. The other program I use a lot is google music. I tried the CloudMuszik to get around this and it was horrible so I actually tried the desktop Zune interface. Again, another horrible experience. It brought my desktop PC to a crawl and would lock up and crash constantly.
Without fully committing to paying for a bunch of apps to get my stuff working, it just seems like a pain if you're hooked into using a lot of google's apps. Granted, if I was going to stay, I would invest in the apps, but I'm not quite there yet.
Just for the record, I'm using the HTC Trophy on Verizon - which is on their 3G network.
Also, if there's something I'm missing, let me know. I'm all for having a more trouble free experience with the phone.