On grass terrain, I think it looks okay, as the grey ties in with most of my scenery objects (hills, ruins, etc) that are a grey rocky colour, and the patches of grass on the base help to tie it in with the green of the citedal battlemat. The hint of brown helps the grey to sit easily with the green grass, where a solid grey might stand out more against it.
The grey goes okay with snowy terrain. The grass is only small patches, so I don't think it overpowers the figure base, and the grey ties in with the grey stones and gravel that is embedded in the surface of my snow board.
The grey goes nicely with rocky hills (and should go nicely with my brother's rocky wasteland Realm of Battle board)