What do you like best?
I'd say it's an advanced survey tool rather than "super simple": You get LOTS of options from multiple question types to lots of styling options. I like the survey editor a lot: Somehow they managed to list all the numerous options here. You can embed your survey as a badge or a widget, send a direct link through an email or publish it on Twitter and Facebook. They surveys look beautiful too (I loved it that you can use a high-quality background images). The reporting looks very detailed too: You can export all the results in an Excel spreadsheet.
What do you dislike?
I've been using online surveys for ages and I never had to upgrade (at least for my personal use). This one looks a bit too expensive and the free plan looks too limited. I am not sure if I want to pay that much. If you market your product as "Super Simple", you'd think you'd want to target users with lower budgets...
Recommendations to others considering the product
I was using the free trial plan and that's what I'd suggest other users do as well. It could turn out to be a cool tool for your needs: You'll never know until you try and it's very easy to register a free account. You can use a 2-click Facebook auth to register.
What business problems are you solving with the product? What benefits have you realized?
While I loved the user experience, I wasn't clear as to why I would want to switch from my current survey software. I think they need to be doing a better job at making it clear how they are different. I'd sign up if I weren't currently using any alternative, but since I am, I need to be convinced better. You need good reasons to switch from something that does what you need for (almost) free, keeps all your archives and has a familiar interface.