Going off of the other reviews I bought the size that I am (14, L). When I opened the package I thought I would never be able to get them on as they looked so small, however they slipped on just fine and fit perfectly and are high enough up the waist and snug enough that they aren't slipping down. They are lovely and flattering and comfy. I am 5ft 4" with a shorter waist and they are the perfect length for me as well. If you are taller and like them a few cm above the ankle then these are great as well...I would guess anyone from 5ft 2"-5ft 8" would be happy with the length, but that of course depends on your leg length.
They are a stretchy but lightweight material. Not see through.
I gave only 4 stars because I would of really really liked a pocket on each side for my mobile to rest. Most workout leggings now have this feature and for good reason so I can't see why these can't also have them. Because they don't have a pocket I won't be taking them out running. Only using them for inside Pilaties or yoga exercising, or even going out and using them as normal everyday leggings. Other than not having a pocket these are pretty good.