Dynamic Queue is 'cool' until you get the bad premade on your team.

And sure enough, if your team's premade sucks or picks stupidly, the game is already done because it pins you against another premade of the same size most of the time. Otherwise, without premades at all (you know, pretty much impossible now in Ranked) dynamic queue is just solo queue.

EDIT: I feel like if only it matched MMRs as well as party sizes if possible, it would be a somewhat fair match. But alas, I currently doubt it does. It's always either a stomp for either premade.