I've had cheaper touchscreen gloves before and they worked, you could just about open the phone and scroll through contacts. So when I lost them and bought these, I didn't expect much better, but I couldn't have been more wrong. The gloves work just as if you were typing with just your fingers, allowing you to text quickly and simply and without any frustrating mistakes brought on by gloves that aren't accurate enough.
As for the warmth, they're ok, no better and no worse than any other glove of this type. They keep your hands from feeling like they're going to fall off but they will still feel a bit cold, if you absolutely must have completely full-proof gloves you'll have to get some thicker ones, but I think to have the touch screen capability, the little compromise in their warmth is well worth it.