I didn't watch the channel itself when it was on-air as I hardly ever watch live TV, but I enjoyed several of its programmes on iPlayer - Little Britain, Gavin and Stacey, Pramface and a few others. The fact that it's not a channel anymore didn't really affect me, but the relative lack of content as a result of budget cuts has - there are no longer any BBC Three shows that appeal to me.
What seemed to happen sometimes is that a show would start on BBC Three and then move up the channels to BBC One, as it became a big hit. That kind of thing just won't happen anymore, as BBC One won't commission the stuff that BBC Three would, leading to all viewers eventually losing out, not just the ones who watched BBC Three.