Easy to use (even if there are few options of questions), ability to save answers in different ways, allows exporting results into Excel format; it's free! It can be improved with more customization options but I think that we solved our needs at this moment so far by using Survs.
We used survs as part of an internal survey application which allowed us all across departments within our organization to answer simple 10 or 15 question multiple choice survey without spending too much time getting