This isn't exactly what I consider a makeup essential, but if you want a boost in length, it does a good job of that. The key is to make sure when using this product that your lashes appear to have white tips as a result of the primer. The longer the white tips are, the longer your lashes will look when you go over the primer with mascara. You aren't going to get drama, but there is a noticeable difference.
Not so much with volume, though - it adds maybe a bit, but not much. If I try to use a thick layer for more effect, it seems to cause some minimal clumping in mascara that never clumped before, regardless of how long I let the primer set before applying said mascara.
This is the only lash primer I've tried, so I can't say if it's better or worse than any others. I'm impressed enough with the lash lengthening