Guitar is my first and primary instrument. I've been playing synths and teaching electronic music for 20 years now and think we live in incredible times. The VB-1 is impressive, there are enough controls on it's nicely designed UI. The actual sound is decent, you can make interesting tracks.
Pros: interesting sound capabilities, free, big fun factor Cons: if you aren't familiar with playing a bass it will take learning the ideas behind bass playing to get interesting patterns (more below), minimal controls
Here's the deal, real instrument VAs depend on understanding the instrument that is modelled, that said anyone can learn much of this by ear, just listen to music with the instrument you're trying to emulate and you'll pick it up. A lot more could have been done with VB-1 and in time we will see VAs that do a better job. For now the VB-1 is an interesting start.