These are so easy and versatile because you can adapt them to any yarn or hook size. I like making them with WW yarn and a larger hook so they're warmer and take only a couple of hours to make a pair.
I think it's the perfect mindless project for Christmas gifts, especially if you need something last-minute.
Just remember when you use bulkier yarn and larger hooks you won't need as many stitches or rows as called for in the pattern. I'd measure around your wrist and thumb and then allow about an inch or so for stretch but no more than 2-3 ribs (4-6 rows) for thumbhole, you don't want it to be too big. For the extra stitches added on for the top, depending on the bulkiness, I would add no more than 10+1 for turning-depending on how much of your knuckles you want to cover.