I like that it's easy to use, intuitive design of reports, ability to track guest data from a variety of sources (mobile devices/apps).
The software can be complicated at first but once you get familiar with all aspects of the system it becomes super user friendly. One thing we didn't realize was how integrated our POS system is with this - sometimes when guests check into/out they don't have an accurate picture as far as their actual stay dates go. This has caused us some problems with billing some rooms that were not occupied during part of time frames in which there are no charges because those room weren't actually used by guests until later dates than what had been billed to them.