Strengths: Basicly, the fact that they are thinner means two things: firstly, the one the shop tells you, "a reduction in rotational mass" is obviously true in theory, although you wont notice it much, if at all. The main reason for getting them as far as i'm cocerned is the small size. roll them up carfully and they are tiny. I can easily fit two in the back pocket of my top, along with all the other stuff, without it being uncomortable.
Weaknesses: Price. They cost £1 more than standard butyl tubes although I personally think it is worth it.
Some people say that they puncture more, I though I havent experienced this.
Overall: They aint gonna change your life, but theyre worth the small extra cost if only for the decrease in pack size.
Overall: Having tried these a couple of times, I'd definitely not recommend them.
On the first ride, you do notice that the wheel seems easier to accelerate but it's a very slight difference, the type that you can't notice by the end of the ride.
What you do notice is the drastically reduced reduction in pinch puncture resistance which goes from average for a normal tube to non-existant for these.
Basically, if you ride over any big sharp rocks at speed and the tyre pinches against the rim, you can almost guarantee a pinch puncture. Also, with the tubes being thin, they tended to tear too much to be repaired.
If you really want to save weight and don't only ride on tarmac / fireroads, find another way to spend your money...
Overall: Bought one to replace the Specialized tube on my rear last weekend. Been out on one ride since and didn't notice any acceleration difference. In fact I couldn't even tell it was lighter when holding it next to a new specialized tube - can't be a lot in it. One of my friends bought a pair & had punctures front and rear within a week. Doubt it will be so much of a problem for me, I'm a 10 stone XC rider. I'll go back to standard specialized tubes next time, you can buy the everywhere, they are a quid cheaper and have never let me down. Spend your money elsewhere, get a nice light pair of tyres with decent pinch flat protection - any recommendations?