The Roland Cube Street Carrying Bag does exactly what you need it to: give you an easy way to carry around the Cube and protect it at the same time.
Use: I play street music in a dense urban setting; electric or acoustic guitar and a single mic.
Pros:
Fit - the case wraps the Cube perfectly. What I didn't know from the description is that you don't ever have to take the case off! The front is opens via zip/velcro and folds completely back, give you access to everything you need, even the power etc on the very back. So setup/tear-down is really fast.
Quality - it's just pleather, but it works fine. For the price it's what I expected. Unless you're careless with your gear it should hold up for a long time.
Couple extras - Shoulder strap works fine, couple of side pockets (no closure) that can hold batteries or the power cable.
Cons:
nothing really. it is as-described and a good value for the money.