DD has shoulder length bobbed hair, which is very fine and has a bit of wave in it, the front ends seem to get very matted (she sucks and plays with it) and the tangle teezer is useless for that part, gentle use of a wide toothed comb is all that will sort it. Once the knots are out it's great for giving it a really good smooth all over though. It also makes DS's short thick wiry hair look really smart.
My hair is fine, wavy and lots of it (just below shoulder), the tangle teezer goes through it ok when wet (but so does a wide tooth comb), but I have to use the comb first when its dry. We all prefer it to a conventional brush once the tangles are already combed out. So, it's a great brush, but not terribly good for knots and tangles IMO.