i dont think so. i was lvl 15 when i got to marleybone. i finished it at lvl 30 and went on to mooshu which i beat at lvl 40. then beat dragonspyre at lvl 45, and celestia at lvl 59. so no, your not to low lvl to be in mooshu in my opinion
You probably should be at least level 27 for that. Satyr (level 26) will be a big help in Marleybone, as will Regenerate (level 28).
Skipping side quests isn't a good idea in this game, unless you always travel with groups. You should probably go back to Krokotopia and Wizard City and clean those up.
Well yah, I figured I was a little below. Now, I've finished Knight's Ct, Katz's Lab, and both Counterweight towers. I'm lvl 27 and when I finish Big Ben and turn in The Last Meow, Stray Cat Strut, and Bad News, I'll be lvl 28 and able to get Regenerate. So, assuming that all works out, I'd enter MS at Level 28. That's not too bad right?
I went to Knight's Court at lvl 25. And I finished Marleybone at Level 27 on my ice . Maybe you should level up a little bit more, the other dungeons, you need to be a little bit higher level so you won't have much of a problem. :-)