I'm guessing some people may be anticipating a full-on Damon fest, a-la Gorrilaz or The Good, The Bad and The Queen, and will be extremely disappointed when they hear Rocket Juice... Albarn's role in this is more catalyst and musical director for what has already been pinned accurately as a very loose funk record with a heavy north African, Fela Kuti flavour.
But if you can put aside your expectations, it's actually extremely good. Tony Allen and Flea lock together to create a groove so solid you could set your watch by it, allowing Albarn and his guests the luxury of laying whatever they want over it without worrying about the back beat. For instance On Night Watch and Forward Sweep, which are essentially a series of keyboard washes and tones that go nowhere, in the grand funk tradition they rely on 'feel' rather than melody, but its engaging stuff. None of this bad, but if you're hoping for the winsome pretty melodies that Albarn is known for they're in short supply (indeed, his voice doesn't appear until the middle of album).
Also, a lot of the tracks are relatively short - hence the 18 song count - and feel impressionistic, rather than carefully worked out, a sort of first take "That feels kinda nice, let's keep it" vibe. Also, even where a vocal track does seem to be building up a head of steam ie Follow-Fashion, the song is allowed to stumble to a halt for no good reason, which can be annoying if you're enjoying the number, but also means that nothing here outstays its welcome.
So, perhaps for these reasons, Rocket... can feel a little slight - I guess that's what happens when you're more concerned with capturing a musical moment, rather than trying to meticulously create one - but taken on its own terms, it's a great album.