I gave it a listen one day back when Ron & Fez were on vacation.
To me it sounded like a typical morning zoo type talk show, only they could throw the F word out.
The reason you thought it sounded like "morning zoo" stuff is because Rich Davis is one of the hosts on The Morning Mash-Up on Hits 1. He brings topics from there to the show sometimes, but generally they try to keep it more guy oriented.
The Show has changed a lot in 5 years. When they were younger they were still in the young guy vibe (chasing tail, going out, partying, etc.) even though they were in stable relationships. Then there was a year or so when the guys were single, and the show was different. They talked about their "ass-capades" which lent itself to crazy stories and advice on how to get women. Then there was a year where their producer was trying to become not-so-lame, and they spent a lot of time trying to help him while at the same time making fun of him. Now, all three are in stable relationships, and Covino is going to be a father. The Show will be taking another new turn because of it.
I will say that ever since they lost the Maxim Radio channel, the quality and number of guests has gone down. They used to bring in all sorts of musicians, hot girls (famous or not), actors, and athletes. Now they basically take the leftovers of whichever celebs are coming in to see Howard/O&A providing they are someone guys would like to hear interviewed. C&R are still Maxim Radio, but they just don't get much help from them other than a few live spots during the year (although they are mainly supported by Budweiser rather than Maxim itself).
Since the guys are getting older, and since their show is driven by the things they experience and see in their everyday lives, it's not going to appeal to younger people quite as much. The guys are maturing which means that they are better interviewers and banterers, but they aren't going to have that raw, young vibe that they used to have.
I still think it's a great show, and they make me laugh every day. However, I'm right in the middle of their age range (Rich is 29, I'm 31, and Covino is 33), I'm one of the moderators of their forum, and I've met them in person 5 times...so I suppose I'm pretty biased. Still, if you're a guy, I'm sure there's something you will enjoy if you listen long enough...you just have to give it a chance.