RIM's answer to the iphone's App Store is up and running and it looks great.
It has already been updated twice from 22.214.171.124 to 126.96.36.199 to solve some apparent connection issues (which I never experienced).
The user interface is slick and it is easy to find, download and install apps. You'll need a PayPal account to pay though.
To get the latest version of BlackBerry AppWorld, go here in your BB browser: http://mobile.blackberry.com or you can click the 'BlackBerry Help' icon. Its the one that looks like 3 gold plus signs.
I've downloaded and installed Shazam which is very cool. It listens to a song and tells you what it is, who sang it and a bunch of other info.
I also dl'd a game called Paper Airplane which is super fun. Its pretty much a clone of that Helicopter game where you hold the mouse button to go up and release to drop down while dodging obstacles. Very addictive. My current high score is: 4209...and yes, that IS a challenge.
Anyway, give it a go and let me know what apps you've tried!