Pros - 6 weeks into the nightly treatment long, luscious lashes emerge. They are stronger, darker and pronounced. They last for about 6 weeks.
Cons - tiny painless blister looking bubbles appeared on one of my lid lines, but I'll take that side effect. Two months after the bottle is empty, you're back to your old short lashes and have to buy a new bottle. So essentially, you are signing up for a nightly self treatment for at least 9 months of the year - which is a pain but hey, we're vain, and my lashes look awesome.
They did get too long if there's such a thing, which results in them pointing in different directions and taking more effort when using makeup. But hey, still vavoom lashes where previously they were not.