These compression pants are a great alternative to the more expensive compression pants you'd find from Nike, Under Armour, etc. and, while I love those brands as well, I don't feel like dishing out that much. These compression pants work as well as any other ones I've worn - snug fit, covers the entire leg, sun protection, and keeps you COOL! I wear these to work out at the gym as well as yoga and they perform incredibly. Their moisture wicking properties are top quality and very easy care - just throw in the laundry, line dry, and they're good to go.
As far as sizing goes, definitely go for the one size up than what you would normally get. For example I am 6'3", 175 lbs, 32 in waist and the large fits me perfectly.
I have 2 pairs of these in black and gray and will be looking to get more in the future. For ~$13.99 if you are considering these, go for it and give them a try, you will be pretty surprised at the quality here.