Every time Chael Sonnen gets on one of his rolls, trash talking Anderson Silva or whatever unfortunate soul his focus lands on, it splits the MMA audience. Some fans feel that Sonnen's talk is brilliant marketing while another segment of the fanbase thinks it cheapens the sport and lowers it a little too close to pro-wrestling.
You can put UFC president Dana White firmly in the camp that thinks it is brilliant (via Heavy):
"(I've never seen) even anywhere near him," White told HeavyMMA. "Seriously - and everybody's going to go crazy over this - but I've never seen anyone who can talk like this guy can since Muhammad Ali. Seriously. Since Muhammad Ali - the stuff that just comes right off the top of his head, and is hilarious. And you don't know what's real and what's not real."
Sonnen is similar to Ali in that both men take their cues from pro wrestling (Ali with Gorgeous George, Sonnen with Roddy Pipper) and both use a lot of clearly pre-scripted lines.
It's just hard to directly compare anyone to Ali given the cultural gravity of most everything he did.