Well, I was all excited about getting the 3125 phone I rushed around town the day it was released to buy one.
After all that I ended up returning it a week later. I couldn't get used to the side buttons. EVERY TIME I opened the phone the volume button would be pressed and that just annoyed me.
Also, the phone is just wide enough were texting with one hand wasn't convienient (and I have long fingers) -- resulting in my having to hold the phone with both hands.
Another thing I didn't like was the 'cheap' internal display -- It's truely not as good as the 2125.
What did I like? I liked the way it fit in my pocket, the response time of the texting was great and the way people reacted when they saw it.
After all that, I decided that the phone wasn't for me and I'd wait for a slimmer sexier version of the 2125 or a device that was geared more as a MUSIC/video player than the current devices.