He works hard and has been doing this for a long time. You can tell he's well prepared but, he's just not that funny.
His delivery is overly shouty to the point of being annoying. He has strange body language sometimes, like how he grips the mic very tightly and holds his elbow up and out, it's like he's flexing his forearm at the crowd the whole time... it's weird, like a nervous comic thing but he's supposed to be this long term vet of the business and the way he talks about comedy on his podcast you'd think he was in the top tier of stand up comedy.
All that could be forgiven though if not for one thing, his material is pretty bland and at times very shallow. If you've seen his podcast you've heard all of these jokes before. To quote Joe himself "there's an originality problem".
I love his podcast, enjoy his UFC commentating, actually liked Newsradio, but have never been a fan of his stand up. I keep trying to give it a chance because of how he talks about the "process" of creating standup like he's an all time great but I constantly get disappointed but what he puts out on stage. He clearly doesn't have a lot of self awareness when it comes to his standup abilities (dunning kruger effect in action) and I'm starting to think the majority of his comedy fans (and high ratings) are coming from his die hard podcast followers who are more than a little biased.
Watch for yourself though... always.