After reading some other reviews I nearly didn't buy this case. However, I am very happy that I did.
The case is well made and does feel durable and tough as described. Sure, the additional clip that comes with it doesnt feel anywhere near as sturdy as most others I own, but it will be sturdy enough for most people and the case is worth £ without it. It's advertised as waterproof and it would definately survive the odd light shower or being dropped in a small puddle for a second or two. Clearly, all zips leak water eventually, but this is going to be case for most other cases as well. I own a Lowe Pro case, for example, with a removeable waterproof cover, but even this wouldn't survive being submerged in water as it doesnt seal it all the way around. This case will fit inside a decent size pocket and I can't ever imagine being caught up in a torrential downpour with this camera and no waterproof coat or rucksack to place it in.
With regards to size, it fit the TZ10 perfectly (snug and not rattling around, but definately not too tight). I have tried to put a spare battery in and can confirm that it does just about fit if you put the lens at the top. However, this offers less cushioning to the lens and, as the battery isnt even secured, I wouldnt recommend it as a permanent solution. I have looked at other cases with better storage for the spare battery but they were all too big to put in a pocket. To me, this completely defeats the point of the TZ10 - a pocket size camera. If I wanted to carry a camera about, I'd take my DSLR!
So is this case right for you? Basicaly, it comes down to this: do you want a case that will fit in your pocket but doesnt offer storage for a spare battery, or do you want a larger case that probably wont fit in your pocket but will store the battery. The choice is yours.