For the price you pay for this, you're getting a really solid well-integrated add-on that offers a lot of functionality I've found lacking in addon ticket systems in the past. The fact that it also comes with a simple knowledgebase is just another perk that makes it worth buying.
This may not take the place of a full time support desk solution like Kayako or others, but it's damn near close, and the integration makes it better for communities in my opinion.