What do you like best?
I like that four eyes is a simple, no-frills kinda platform. It gets to the point without the need for flash. The platform is free, gives you almost everything that you need, and gives you a wealth of options for survey question choices.
What do you dislike?
It's good but it's not an end-all. Sometimes you have to find creative work-arounds because it may not have all of the question format types you want. I would ideally like to ask a question and have recipients choose only some of the answers which they can then rank. Alas, this doesn't exist and a few other survey question formats that aren't there.
Recommendations to others considering the product:
Go for it. It's free to use and very effective. I got a rec from Joanna of Copyhackers and I've not looked back. Delightful system.
What problems are you solving with the product? What benefits have you realized?
Surveying customers is quick, easy and effective. The benefits are it's fairly pain-free and not to mention, free, to create a survey for customers.