I recently ordered two of the small bottles of this (along with the matching EDT- reviewed separately), during one of the recent promotions from Philosophy.com. I only use this on my arms, and only to have a way of layering my fragrance. I keep one on my desk, and one in my bathroom so that I can use it whenever I feel like it. I absolutely LOVE the Falling In Love Summer scent!
I can't say that I see or feel much in the way of a "firming" action, but I can say that it really has made my arms (even my elbows) very soft. I find myself using this on my hands as well, because it absorbs instantly with no greasy after feel whatsoever.
If you would like to try this for yourself to see if it gives you the results that you're looking for, I highly recommend either ordering the small bottle from Philosophy's website, or asking for a sample the next time you go to Sephora. I took one lippie off for the price, but if I wanted to continue layering this lovely scent as I have been, I would purchase at least the small bottle of this again.