I got my 7100t late last year, as our company was considering switching to Blackberry devices, and possible getting BES (My Boss' idea). I'm the IS guy here, so I get to play with the gadgets
Before the 7100t I had an MS Smartphone device, which I was very happy with - until I broke it :(
Anyway, my Boss got a 7100t about a week after me, but as of last week he has ditched his in favor of a Treo 650 - he decided the 7100 was too quirky.
I shall also be switching from my 7100t once I decide which MS Smartphone to get again. I found the Blackberry to be quirky initially, but put that down to just being used to the Smartphone OS previously. However, from getting the 7100t until now, I've been more unhappy with it than happy. The things that bug me are:
Bluetooth support - It does not link automatically with my Bluetooth car kit. Well, it does, but when I make or receive a call, the 7100t doesn't put the call through the kit. For that to work, I have to initiate a Bluetooth connection from the 7100t before I switch my car on, everytime. It's getting annoying. :( I've tried Trusted/Untrusted, Headset/Handsfree, Encrypted/Unencrypted, upgrading the firmware on the 7100... nothing. My partner's Motorola T720, My old smartphone, and my collegues new smartphone all connect seamlessly, exactly how it should be.
Suretype - I'm fairly impressed with this, except that it's a little slow, and also if you mis-type something and then backup to correct it, the 7100 decides to pick a different word from it's dictionary to match to this time around. Frustrating.
Profiles - When successfully linked to the car kit via bluetooth, I'd like the 7100 to automatically switch to a different profile (One I created, called "Car"), which turns it's ringer off (since the car kit "rings"), and changes some of the other sounds too. Not a major problem, but it would be nice.
Receiving Calls - I may have not read the manual on this bit (!) but incoming caller ID is displayed in a large font, and I don't get to see the whole name of the person calling (Not a problem, unless like me you have two people with the same first name, and same first few characters of their last name!)
Speakerphone - The 7100 "sticks" in the last mode you used it. (Well, mine does!). If you activate the speakerphone and hang up the call, next time you are on a call, the speakerphone won't work first time around, you have to switch to speakerphone, switch back to handset, and then switch to speakerphone again for it to work. (OR just remember to switch FROM speakerphone back to handset before you end your previous call)
Don't get me wrong, by no means do I hate the Blackberry... but I think it's not for me. I like the freedom of the Smartphone, and the fact it can sync to our Exchange 2003 server without BES or without having to run a program on my desktop PC (& therefore leaving myself logged in all the time).
Just my 2 cents