To me, it&#x27;s the fact that Mirth nickel-and-dimes users for &quot;premium&quot; features and has pretty poor documentation to push people towards support plans. It&#x27;s an open source platform &quot;kind of&quot;, which rubs some folks the wrong way.<p>However, the functionality of the engine itself is top notch. We&#x27;ve had some Mirth servers running for a year at this point without incident. It handles alot of things around the nuances of HL7 nonchalantly, which has usually been my hang-up with non-healthcare specific toolsets like Mule or Camel.