Our son is at Hillside and we have been very impressed. He has made lots of friends, speech has come along amazingly (he spoke very little before going to Hillside), he has built confidence and the teachers have encouraged him to try different activities. He has 20 children in his K1 class, but with 3 teachers (2 teachers aides and the main teacher) he is definitely getting supervision and attention to help his development. The kids have access to computers daily, have a library day and we also get a weekly newsletter with information about what the kids have been up to during the week. In K1 they haven't focussed on a lot of mandarin, but he seems to know colours and they did a large unit on Chinese New Year celebrations. We have had great communication between the teacher when required and a communication diary comes home every day.
At a teacher/parent/child level, we have found Hillside outstanding so far.
If you asked me what my biggest problem was with the school I would say the attitude of the principal could be better, but that is relatively minor as he doesn't seem to have much to do with the class level.
Our daughter went to ESF Sheung Wan before it became Hillside for K2 and they did a great job in preparing her for primary school, so I am hoping the same will be true of Hillside.