Mayhem is Gaga's best album since Born this Way. It has some of her best songs ever: the singles + Garden of Eden, Shadow of a Man and Perfect Celebrity.
I'm pretty satisfied with the record, but I'm giving it a 4 star rating still coz I wasn't too fond of Vanish into you, Don't Call Tonight, The Beast and Blade of Grass. They're not horrible songs, but a bit too safe and familiar.
Another thing is that it was marketed as something a lot grungier and chaotic than what it actually sounds. Other than Disease and Abracadabra, I think Perfect Celebrity and Killah do the album title some justice.
Regardless of its weaker parts, Mayhem is nevertheless a solid album that deserves recognition and exposure. Those who gave it a negative review after a listen or two, are not being fair. Music needs to be heard several times before we can start processing and appreciating it. My favorite tracks might even change after every listen. So give it time people.