It works, as do other plants with strong, lemon-y smells (like citronella and geraniums) but the problem with those concoctions is that they don't last long. I've used them a lot in the past and at most they'll last an hour or so. Their problem as far as I can tell is that they evaporate quickly and once you can't smell them anymore nor can the mosquitoes, and you're fair game again.

DEET is so effective because its effects last a long time. In my experience it basically lasts until I wash or go for a swim, so for as long as it's on my skin. Granted, since I normally use it in the summer months when I'm likely to swim daily it doesn't last more than a day in practice, but that's already far longer than any of the plant-based ones I've tried.