I have made repeated attempts to get into aperture since it was first launched.
However as other individual products do individual aspects better (Capture NX for RAW conversion, CS2 (3 soon) I use it less and less. That leaves it as an archival system - but then many web galleries allow that too, (although theft is a concern here too) and I do not need to be on my own computer!
It all stems around Apples initial idea to lock everything into the database. Yes, it keeps all the various files togeather but very few photographers are going to trust their files to a system. And thats because it is very difficult to get RAW files OUT of the database and Apple is not the best convertor.
So the referenced database system was launched and is better for finding files but it defeats the object as I still have several versions of all my images that I have to remember to upload into the database.
So I will keep trying with aperture but time is running out!