I've been knitting socks for years, and use either bamboo or metal needles. I tried these out of curiosity, and was pleasantly surprised.
There's nothing that compares to the feel of bamboo needles, but I usually switch to metal when picking up gusset stitches or doing decreases. This avoids putting strain on the bamboo needles, which can be costly, and can bend over time. These plastic needles are sturdy enough for these tasks, and the stitches stay on the needles better than on metal ones. Knitting is fast, and the stitches glide along.
I think these needles are a good buy for new and experienced knitters.