I had a seminar observed by a lecturer last year, and he was very good with his feedback. I did get the impression, though, that there was absolutely no procedure for supporting TAs and that I was only being observed because I'd asked to be. It seems to be very inconsistent, depending on the course leader.
I think the answer is to be proactive: ask to be observed, for your questionnaire scores etc. Even simply ask the students. Half-way through the last semester, I gave my students an informal feedback sheet to ask them what they thought was good/what I could do better. This way, I got lots of helpful feedback and ideas I could act upon, alongside reassurance that I wasn't totally crap.
I do wish departments would give more guidance and support to new teachers.