The best place to post feedback is on our forums here.
A note about feedback from our Community Team:
Here at Robot we like to try out innovative solutions to problems and see what fits best. We love hearing you all talking about those changes. In fact, a large part of what the community team does at Robot is compiling all of your thoughts and criticism for everyone in the studio to read and discuss -- it's that important to us. Many of the changes we've made as well as some of the changes currently being discussed around the studio are thanks to you: the community.
However, when posting feedback -- whether it be negative or positive -- please be sure that feedback is constructive. For example, if you feel like a hero's new animations are clunky and unfun, let us know why you feel like it's unfun or clunky. Telling us that Ivy's new animation "sucks" is not helpful for us and ultimately, for you. Telling us why it feels clunky or unfun ("I have to stop to cast it, breaking the flow of combat!") gives us a place to start when examining that piece of feedback.
If we feel like a comment is just flat-out antagonistic or non-constructive to the discussion, it may be removed with a polite PM. This is an effort to keep the forums a home for productive discussions for both community members and developers.