I take them. Wish I could tell you whether they were efficacious, but I started them alongside a ****tail of other herbals (eleuthero, schisandra, sarsaparilla, suma, and maral). I remember feeling that I had more energy soon after taking my first rhodiola capsule (I started taking them in the morning instead of the evening for this reason) and my herbal regimen has definitely improved my strength, endurance and sense of overall well-being. I recommend trying it if you're interested, it's a very affordable supplement!
If you're interested in herbal nootrophics, you may also want to try Brahmi (Bacopa monnieri). I've personally had good results.