I'm not at all familiar with the itunes import process. But I can give you some general info.
First, all playlists that you import should end up in the Imported Playlists group. Look under Playlists, it's a few down from the top. Your itunes playlists *might* be there.
You can transfer playlists from itunes, one at a time, by exporting them from itunes, and then importing the files that itunes exported. If you have a lot of playlists, this will be tedious. If you've only got 4 or 5 that are important, it should be pretty easy to do.
For itunes smartlists (or whatever they are called), you will want to recreate these in MC. I think if you export a smartlist in itunes, it just gives you the files that match, but NOT the definition. Which is a waste of your time, since you probably want the list to auto update every time something in your library changes to match your smartlist.
Finally, you may find that the increased capabilities of MC mean that you don't need some of your itunes playlists. Itunes is very playlist driven to do almost *anything* advanced. In MC there are usually better ways of organizing things than building yet another playlist. Explore MC's features, views, etc, and you may be pleasantly surprised.
Good luck,
Brian.