I believe this one took me 43 moves/slides. Did you design the puzzle yourself or take it from another creator like Binary Arts / Think Fun? They are the creators of the original Rush Hour game of 6x6 sliding puzzle games. You should give your three Unblock Me levels difficulty ratings and/or a challenge to complete them under a certain number of steps. As they stand now, they do look a bit too much like copies. If this was original work and not just a random copy or splattering of two and three block units to move, then well done. I would come back and give a review in that case.
@nGord Actually, I designed it myself and did not take from Binary Arts or Think Fun or something. I actually don't know about those creators... well, I have played this kind of puzzle game in a mobile app/game before but it was long ago and I have already forgot the developer. Anyhow, thanks for playing! and I'll take your suggestion and use it next time.
As mentioned in your Unblock Me 3 - thank you for the original puzzle! This one took me the longest. I'm looking forward to perhaps grander designs. Thanks for sharing!