It's a supergroup in name only because the various parts are so disparate and, ironically, because of their distinct entities they do not gel in any knock-out symbiosis - they do their things together and effectively but still distinctively and as a listener I think you either like those individual bits that you hear in the mix rather than appreciate as some genuine amalgamation of talents.
The grouping of Mick Jagger, Josh Stone, AR Raham, Dave Stewart and Damian Marley is significant but ultimately singular in that each plays spotlight parts rather than casts a broad beam of unified light. And occasionally the voices fight with rather than complement one another.
I quite like Mick Jagger solo and if you share this view than the Superheavy vehicle will appeal even more because at times it is Mick clearly driving. For example, Energy apes guitar licks from Under Cover of the Night, and I Don't Mind could be from any Jagger solo album. Single Miracle Worker works a formulaic rather than miraculous reggae beat to reasonable effect with Jagger and Stone vocals offering their recognisable qualities.
All this said, I quite like title track Superheavy with its reggae-rap and beat as well as Joss Stone's soulful interjections. Indeed, I quite like Joss Stone, and her increasing maturity as an artist takes further steps here with creditable vocal contributions adding to the overall impact. This isn't ever going to be a great album, but it is full of production and earnest endeavour, and in the background it will still rock your incidental listening.