I couldn't afford the 2-3k it costs for an authentic Roland TB-303, so I settled for this instead. It has identical functionality and interface, so there's nothing amiss there. I personally like how it can be propped-up so that it faces the user more directly, which is handy in studios where there's little desk space and this gets place further away.
I have noticed though that it's not an identical copy of the TB-303 when it comes to sound. Listening to online comparisons there is a noticeable difference, one of which concerns the "accent" feature. Read up on that online if this concerns you, but for the difference in cost I certainly feel the TB-03 is worth it.