Good product & helpful support!
I'm not a professional web designer, but I used Instapage to build landing pages for the last 6 months. I loved its features (heatmaps, form-specific conversion tracking, high customizability), and what I was able to design through it. My biggest complaint is about how it formats pages for mobile--they always looked totally wrong and I would spend hours reformatting/respacing them. You'd think that the platform would be intelligent enough to transfer your design, but it always messed it up. Other than that, I've enjoyed it--plus customer support has been very helpful at processing requests and fix bugs!