The roads/rivers are 300mm long and 50mm wide and have a very flexible rubber base which will easily lay flat over obstacles/hills. So for my £45 I got 10 feet of road plus the junctions and five feet of river plus the bend and junction which I think is a pretty good deal. They are made to order so take a bit longer to arrive but the timescale he quotes is accurate.
What do I think of them? I think they're great and I'm already considering buying more. Also one of the guys I game with liked them so much he ordered some too. I'd give them 9/10. Here's some shots of them in 'action'.