I got one as a Groupon deal a while ago, and it was rubbish.
It was tiny - I got it for my husband in a size Large to go over a jumper, but it was an Asian size and probably a woman's size 8/10. It needed a power pack to work, which had to be sourced separately. I didn't bother trying, as it was no use to us. I tried to return it, but the retailer said to keep it and gave me a refund, so they must have been very cheap to produce.
I put it on Freecycle, and a woman took it for her son who had started an apprenticeship as a gardener. I didn't know her, so have mo idea whether it was any use to him.
So, based on that, I would suggest that you only buy one you've tried on, and look for one with a USB port so you can charge it, rather than have to carry a power pack at all times. Some may be better, obviously, and technology has moved on since then - just be sure you know what you're buying.
