K, I've never found too much to bitch about with TF2 unlocks, but the mini-sentry disappointments me. Greatly.
I guess the idea is that you can get it out their faster than a normal sentry, but it's not worth it. It's an out right downgrade of the sentry. If it actually replaced the normal sentry on the PDA, then I would be steaming pissed.
This combined with no new (real) buildings makes me a sad, sad doctor.