Yes. I use the 'Other' setting on my AW when working out with weights.
No I don't think it's very accurate. I also use a heart rate strap, and the Polar Beat app, set to 'Strength Training'. The AW calorie total is usually around half that on the Polar Beat app. As the Polar Beat app has a dedicated setting for strength training, I prefer its figures.
I do think chest straps provide more accurate heart rate data, especially for strength training, not least because as your wrist flexes under load readings seem to be affected.
I've also noticed that AW heart readings and chest strap heart readings do not match that closely.