I use the on-prem version in many different variations.
Speed, integration into existing applications, ease of management among other things.
Not many things come to light. If I do have an issue, their support either provides an alternate solution or create a hotfix
I've tested this helpdesk and was really pleased with it and it was in my top-3 list. We ended up with Zendesk but that was only because of the ability to create and write custom apps inside Zendesk, like displaying additional information about the user as a panel next to the ticket. If we will decide to go from Zendesk to another helpdesk platform, will consider JitBit again because they are not limiting file size for email attachments like Zendesk is doing.
all essential features included, email attachments are NOT limited to max 7mb like in Zendesk, source code option is available
no online chat option, no web widget to submit tickets, no "organizations" for customers, no PHP version, no custom widgets