The main hold up with apps is a lot of developers (myself included) are not willing to post their apps for sale until they have had a chance to test them on actual hardware.
I got my PlayBook and tested all of my apps before they were posted. As more developers get their hardware you will see more apps.
Not well enough to catch all bugs. Plus the computer you use can really effect it also. Like if your computer isn't running the sim as fast as it should you might have timing issues when you run your app on an actual pb. That was something a friend of mine ran into with his app.