Well, I've never really been impressed with Hornby's details; I've always found them to be quite flat when it comes to details on the buildings, although the rolling stock is of good quality and build.
However, this coal stage I went out and brought for my railway around 6 months ago and find that it fits in quite well, I've used it for my engine yard area as I only run tank engines as it's short branch line, I've weathered it down slightly and find that it helps the overall effect of the plastic being slightly dulled down, although it's not shiny, I found that it was still slightly plastic looking.
The dimensions are:
Height I can't remember but I think it's between about 50 and 60mm .
If you want to build a finely detailed railway, then this may not be for you, id scratch build one. However if this is a first attempt at a railway or as a gift to someone else. It's worth it.
I've found them for as cheap as about £1.50 on eBay, but you can pay up to £12 or £15 in some model shops.