These two releases add more weight to the opinion that Ian Carr is incredibly under-rated as a jazz instrumentalist and composer. It might be fusion, but this music was played with a great "groove" and the tunes were often memorable.
Labyrinth is the stronger album of the two, despite veering into "concept album" territory. However, don't expect self-indugence. Roots is more like "Sweeney" (70s UK cop drama) music, funky, but with the inevitable twisted jazzy melodic line/hook that Nucleus' music has. On Roots Ian has given the rest of the band the chance to write a tune, and they're ok, but not a patch on the contributions of Karl Jenkins and earlier Nuclues alumni (on the first album "Elastic Rock" for instance).
If you like creative, lyrical, groovy, feel-good improvised music, then you won't go far wrong here. Incidently, if you've not heard Elastic Rock (1970 debut), just buy it while you're buying this. You'll be playing them round the clock for the next week!