I think bugs are being fixed all the time, as people find them. Obviously some are more complex and harder to fix than others and so will take longer though.
Adding features is to increase the scope of DB and make it able to simulate a more diverse variety of situations. Plus I am thinking it's probably more fun to add new features than just fix the old ones all the time! :D
If you find any errors or bugs you should post them on the Bug Board; it will help [Num],[PY] and co to fix any errors in the program.
And welcome to the boards!