Depends how much you do really.
It can be a happy K-trip (not recommended doing outside at a rave or w.e for example)
I did a big dab of mdma round a friends, then i took some ket and i was just this ketamong/etarded snake crawling on her floor hugging her speakers where the trance was coming out of.
So yeah, it really gives you good humiliation in front of your friends lol.
But if you do it at a rave, you'd obviously be doing a bit less, so what i find mainly is you get the euphoria of the mdma, but you also get that great euphoria from the ketamine, plus you have Dual Music appreciation going on and its wonky and fun to dance :D