I have a very early No!No! model bought for about £50 in a Debenhams sale and I'll admit I didn't use it religiously at first. Then I went back to it the following summer and managed to get my lower leg virtually hair free, but it is a commitment. Mine is mains operated only, which doesn't bother me, in fact it means it's always ready to use I suppose. So if you have gadgets gathering dust in the cupboard I wouldn't go for it because you have to use it every couple of days for months. In the summer, though, it's only akin to shaving legs every time stubble comes through.
The other thing they should emphasise is that the burning (thermacon technology in NoNo speak) doesn't completely remove the hair even though it may be killing the root, so the legs don't instantly feel smooth after use. They provide a buffer to smooth away the remaining burnt stubble, use this gently because it can feel like sunburn if you scrub too firmly. I didn't bother because my stubbly remains weren't really visible even though I could feel it.
Now I'm faced with a dilemma; my NoNo doesn't work on the bikini line as it's head is too wide so do I go for the TSV to tackle this and the underarms actual area? Hmmm. I tried the model I have under my arms but it felt too hot and I gave up; my NoNo only has one heat setting.
Finally, I'd never removed my arm hair as it wasn't visible. I tried my NoNo on my lower arms and in a single use all my are hair was gone and has never grown back so I wonder whether the same is true on virgin leg hair, if you know anyone who has never ever shaved, waxed or otherwise removed their leg hair?
I'm always the lone voice recommending NoNo whenever there's a TSV, it worked for me but need commitment. HTH.