Simply put HikaShop's support is the best I have ever experienced. I am using the free version of their extension and it is great by itself but what makes it stand out is the customer service.
When I use free extensions and have a question I am accustomed to waiting a long time for an answer, getting poor responses, or no response at all. With HikaShop I simply registered on their forums, posted my question and got answers. Not only did I get them, they were helpful and fast.
Some users who have given poor reviews may be overwhelmed by the amount of options that can be configured, but in my opinion the options are what makes HikaShop great.