I had no problems w/ Froyo the phone was amazing, I never had any random reboots & the speed seemed good. I wasn't using data then, and I had launcher pro & everything was frozen w/ titanium backup so I could go 2 days without charging.
With GB I get random reboots when I listen to music, but I'm satisfied with the phone it is a bit smoother than before & it loads everything quicker. I use my data connection for e-mails now, and without fail even without making calls it will be down to 20% by the end of the day. It doesn't bother me too much since I'm not a power user. I have laucher pro on it but I don't know what to freeze since I upgraded. My gallery started using alot of data as well. But Overall I don't regret GB.