I love this synth. I'm a big fan of the Oberheim sound and feel, and this is an excellent rendition of it.
The sound is very lush, and very "analog" - you can get very deep, thick sounds, or reedy thin sounds. The onboard effects, while not part of the actual SEM product, are very useful and appropriate.
Most things about this device are about as perfect as one could imagine them being; it's very easy to use, very easy to control, very easy to play with.
The modulation matrix and voice programmer are very useful and extraordinarily powerful, probably easier to use in the SEM than any other Arturia synth. I would have hoped that the number of outputs would have matched the inputs (which would have enabled sample and hold, for example) but no luck; this is a very small criticism, in the end.
There are bigger-sounding, possibly more faithful SEM emulators out there - Sonic Projects' OP-X, for example - but the Arturia SEM-V is easier to use in my opinion, and well worth the investment.