The program doesn't really say anything about the size or quality of a project. Some of the best and most complicated albums (lots of automation, strange FX, doubling etc.) are made entirely without a digital sequencer like Cubase. However, if you want to know all that you can do with Cubase, that's another thing, which would take many, many pages, if not books, to explain.
Also, I'd say the sequencer has about the least of all things an effect on the quality of a song. You get "decent" from a decent musician using decent mics into decent preamps used with a decent amount of skill recording on a decent format, and so on and so on, all without using even a single byte.