We done the outer Hebrides in May fantastic weather, the beaches are amazing, but the lack of trees, bushes, and flowers didn't do it for my wife.
You can certainly see how bleak it could get in the winter.
We also managed to get to the isle of sky which had lots of trees ect, the misses was much more happy.
But I loved it all ,we are in Essex and did 2200 mile round trip in 2 weeks, we will definitely be back to western scotland