I also got the Vibrant on the first day. Was happy with the phone at first, but it seemed to misbehave after getting Froyo. Not sure if that was a coincidence or not. I get so many apps missing, random reboots, slow everything, wifi disable/enable is hit or miss, can't uninstall/install apps when apps are missing. A once-great phone has become a nightmare. All before the phone was a year old.
I was holding out for the SIII, but T-Mo wants about $369 for it and they will do me a favor and allow me to re-commit for 2 years. No thank you. I even considered the Note, but at present time, no solid released date has been set. So, I just ordered a GSM Galaxy Nexus for about the same price as the SIII (minus 2 yr extension). If T-Mo aggressively drops the price on the SIII or the Note becomes worthwhile to buy once offered, I might get one of them and sell the Nexus. I really would prefer a phone with an SD slot.
Not sure why T-Mobile, or any other carrier,would think it's ok to offer new customers better deals than current customers, but it is very off-putting. I'm looking forward to my contract-free Nexus