"Incredible" may not be the word I'd use. That being said, I did think it was pretty good. I was playing mainly with only one other teammate, so I found it a little tough, but there were some genuinely tense-feeling moments, and I was always motivated to go another round once I'd failed. I'd hope that in the finished product we'll see high levels of variation between enemies. By which I mean, when fighting off husks, there are differences to when you're fighting off cerberus minions, besides the skin of whatever you're shooting at.
I think the important thing to remember with the multiplayer, is that while it may not measure up to something like COD multiplayer (even though I found the little time playing me3 much better than the last time I played cod, despite the fact it's a demo. But I'm biased.), it comes with a lengthy (and hopefully brilliant) singleplayer as well.