It's not a rush job. It was shown nearly finished at last year's UK Games Day. SMs are GW's 'Bread and Butter' and a scenery base for them is pretty important and something they'd want to do well not rush and not care about.

Their scenery these days is all on a 2 foot square tile, for use with the realm of battle modular table GW sells. It's constrained by needing to look good on it's own and connected up to others. It looks a bit worse because of that, but I still think it looks decent enough overall myself.