The first album had something really special. The original set of collaborators brought a LOT of creative energy and interest to the project (Miho Hatori in particular, but of course also Del and Automator).

The collaborations on Demon Days weren't as strong. Danger Mouse brought some great sounds, but his productions don't have the level of personality (or even quality imo) as those of Dan Nakamura. Miho and Del were also both absent, so the sort of goofy, playful quality was really pulled back.

I haven't heard anything great from the band since then, with the exception of Plastic Beach, which has a handful of really good cuts, and is a more cohesive album than most of the stuff since DD.

It seems like Damon is just wanting to collaborate with a lot of different people, but he's not picking artists with very strong, unique voices comparable to the original Gorillaz. The albums end up being just sort of left-field-ish pop projects with tons of features, really not too far off a Bruno Mars record.

These days Gorillaz represent average songwriting, good production, inconsistent narrative and style, awesome visuals, and Damon's vocals (which are always solid imo).