Irena, I don't have much in the way of good advice here, but want to wish you good luck with it!
FWIW, our elementary school allowed parents to request teachers, so we did make a request every year. It was probably an easier situation than yours in some ways - we were at a small school (only 2 teachers per grade level), and there were many involved parents so it was easy to get tons of parent perspectives on the pros and cons of each teacher. There was also a bit of cross-teaching going on, so sometimes I'd have already had the chance to have my child exposed to a certain teacher.
That said - when it was time to turn in our request forms, I made sure that what I wrote in the request highlighted what type of teaching style etc worked best for my child rather than just stating that we wanted to request teacher X.
I also found that feedback from other parents varied widely (as another poster mentioned above)... and many times feedback from other parents that I trusted didn't work out the same way for myself or my child if we ended up with that same teacher - for all sorts of reasons, and the 2e piece complicated everything.
That said, overall, I think that in general most parent feedback was reliable re the things such as accessibility of the teacher to parents (were they willing to meet with you, listen to your input etc), were they set in their ways, were they strict or were they so mellow their class was out of control - those types of things.
Good luck - I hope your ds gets a wonderful teacher next year
polarbear
