Lip Injection: Immediate reaction, lips swelled so much and turned bright red from the irritation (it stings a lot and gets really hot for a few minutes), but all the tiny lines and wrinkles disappeared. Very glossy, not too sticky - very sexy, if you like that look. They looked awesome but only for about an hour. The next day they were chapped and the lines of my lips looked blurred (probably were chapped, too.)
Lip Venom: Didn't work as crazy as the Injection, but became a tiny bit more full. A decrease in the lines and wrinkles of the lip, but less than the Injection. It does dry out the lip, so I put Vaseline on top of it. It's a bit sticky though, (I used a colored one, not the clear) and hard to get off of my skin.
City Lips: Awesome! My favorite. It's not an immediate plumper (although it fills in your lips with a shiny gloss right away) and it doesn't sting, but the box says it takes up to 30 nights to see a difference. I have been using it for three weeks and I see a difference. This one is a treatment, not a cosmetic, supposedly, but I use it during hte day in addition to before bed. The bad thing is that you are supposed to use it continuously to maintain the difference. It supposedly stimulates the collagen production in your lips.
My lips are 'plumpier,' as the woman at Sephora said.