I am using the free version as the premium is a little expensive for my needs. Often I only need a very basic form, but if I had a lot of sites needing more complex forms I would certainly consider the Unlimited Lifetime package.
What I like:
The forms look great and perform well. The log of sent messages is very handy. The forms don't have any lag when sending unlike some other forms I have used in the past. Although there are forms out there which load less code per page, when it comes to clicking send - Fluent Forms is super fast!
The support is excellent even in the free version. Don't post support here though, go to the developer’s site. They helped me out a lot with an issue on one site and with some help the solution was found pretty quickly. Impressive that they give great support for the free version.
So far I have found nothing I don't like. Give Fluent Forms a try!