What do you like best?
Site5 makes it very easy to get started. Due to the container structure, it is incredibly simple to get started with, rather than needing to configure a whole server on your own.
What do you dislike?
As a Rails developer, Site5 used to be amazing. They were one of the few companies that offered the whole package of easy deployment and simple domain setup. Those days have long passed though. Ever since their fiasco about the ruby 1.8.7 upgrade. Even after that version had been retired mid-2013, they still lacked any attempt at a fix until later in November. By this point, the switch was over to Ruby 2.0, and more importantly, newer versions of Rails which had compatibility issues with the dated version of Ruby being run. Eventually, the sites I had hosted failed all together, and I still have as of yet to move them over to a better hosting provider.
Recommendations to others considering the product
Site5 can be great, but they have been going downhill recently. If you are looking for something to get your feet wet with customizing the software for webhosting, this could be for you. As it stands, Site5 has made major errors, such as taking multiple years to make the upgrade to any version of Ruby 2, citing that it would "break things", even when it could be a simple opt-in. While they might get better, be weary of the past and make sure that you are not stuck with Site5.
What business problems are you solving with the product? What benefits have you realized?
Needed to get started hosting Rails, and I wasn't disappointed at the time. As time wore on, nothing changed.