From what I've heard, Eminem is a rare case of a rapper who has a lot of funny, not-to-be-taken-seriously songs. Actually, most of his songs are funny songs, like most of SSLP, dark humor in MMLP, Encore, Relapse, and a lot of funny songs in every other album, even if it's set out to be serious. Eminem could basically belong in a comedy rap category. I didn't do the math, but from the top of my head, he has more funny, joking songs than serious songs.
Humor is a risky thing to base your songs on. If someone doesn't share your sense of humor, your entire premise fails. Most of modern criticisms on Eminem are actually because of a failed joke attempt, lines that were supposed to be funny but ended up being bad, either because the joke is actually bad or the one who heard it didn't share that sense of humor and immediately disliked the song. Eminem has a very niche sense of humor and for some it works, for others it doesn't.
Like, for example, Relapse. I love Relapse, but I can understand the hate it gets. I understand people find murder and r--- jokes unappealing. Because of that, the entire album depends on you sharing his sense of humor. Very risky.
Next we have all criticisms of Recovery basically, other then yelling, being about bad puns and punchlines. Again, the premise depends on you sharing his sense of humor.
Same thing with h---: The Sequel, MMLP2, etc. Not to mention Encore, that's the ultimate example of a drugged out Eminem basing his songs on something he thought is funny.
But even today when a lot of people consider Eminem to have fallen off badly, when it comes to actual real, serious songs, he still delivers. In the middle of all serial killer jokes, he got serious on Deja Vu and made an amazing song. It's fair to assume there was more where that came from, it's just that he wanted to do a different kind of album.
The only bad line on Bad Guy is "toilet's clogged cause I'm talking a lot of s---". Another joke attempt and it doesn't fit with the rest of the song at all.
Eminem's humor used to work because it fit at the time with him being edgy, shocking etc. The world has moved on from that, what was funny 15 years ago is outdated now. He can't shock anymore, there's far worse things in the world we're used to by now other than a celebrity joke or pretending to k--- someone and insult women.
Other rappers take themselves seriously and make serious songs. Serious songs are more likely to stand the test of time than a joke that can be funny once and then it's over. Even when Eminem's bragging, he's trying to be funny.
I believe if Eminem focused on being serious for a moment and made a serious album with little attempt to be funny, he can deliver a classic album, full of songs like 8 Mile, Lose Yourself, Deja Vu, Stan, etc.
His serious songs are often met with praise. Even people who lost faith in him can get surprised, as was the case with Bad Guy. Though, modern Eminem has a slight problem with serious songs now, as he's trying to be too technical and fit too many rhymes, the message and fluidity suffers for it. I don't think he'll be doing that on his next album anyways, so that's not my concern now. But if Eminem got serious, he'd still be making great music.
