Very nice,so far! Really impressed.
I like how it's gonna be a way to browse through tilesets for anyone too bored for the level editor,and it's very good to be seeing very smart uses of tilestes.
Yeah,there are problems.Many tilesets are just a huge mess by themselves,and some look ugly.Not ugly enough to stop you,though!
Also,give us the high jump.I don't know if this is a mistake,or you didn't playtest,but some screens (all after 50,iirc) are impossible to get through from the "normal" way.You have to move back from the next checkpoint at these cases,but its a problem with an easy solution,the high jump(or edit the level a bit)
You should definetly continue this! It's really fun!