I've listened to the audiobook version.
The story is sort of interesting. Now the audiobook is abridged, so maybe it's better if I read the whole book, but I had some problems with it. On the one hand I felt that the parts on the planet were very hurried, while the part in space is a lot more detailed. It was also too much running about, and ended up not being all that interesting in the long run. Some elements of the steampunk aspect were nicely used, like when only steam was available or not, but otherwise it seemed a bit forced. The mystery element played out nicely, and the overall story was okay. It just wasn't as exciting as it could have been.
The reading by David Tennant was brilliant as always. Even the way he emulated the steam coming out from the robots was effortless, and sounded genuine.
The original characters didn't make much of an impact on me. Perhaps the ones that I could remember the most were Sally and Jimm. Though that is probably so as they are the two characters most central to the story. As characters, they weren't rounded to me, just plot devices.