I used to use Viewranger on my N95 with a BoxIt case. Great for spontaneously trying new routes but the clamp wasn't up to the job and kept breaking.
Have been looking out for something similar for my Desire so when I saw this I thought I'd give one a go.. ordered it after lunch yesterday and it has turned up today, so can't fault their delivery!
The case fits the phone snuggly which is great as I was worried it would be a generic size and the phone would rattle around in it. The case itself looks very well made with a very fine zip - I think I would describe it as water-resistant rather than waterproof as water could potentially get in where the zip tags meet. The mount is way sturdier than the BoxIt ones, both how it attaches to the bars and how the phone clips to the bars.
So, overall, it's looking like a good buy.. the only negative I can find at the moment is that where the two zip tags meet I think they are going to jangle about a lot which could get annoying..