Yeah, I have a TD-3. It's by no means trivial to use for a novice, but there are some nice guides such as the one linked below. You have to get used to holding the internal state of the sequencer in your head during programming, as there is no display showing which step you are on etc.
And the time mode must be programmed separately, which on several occasions has left me scratching my head at why the thing makes no sound at all.
But yes arguably synth experience won't even help, the 303 sequencer is very weird and unlike any other sequencer