The ability to create custom reports which are easy enough that even our non tech savvy staff can use them with little training! It's also very user friendly if you need help or have questions about it - I've never had an issue getting someone who knows their stuff there in short order when needed!! Not much as far of dislikes but nothing major either.
We're using this software at my hotel so we don't really get any benefits from other vendors like HomeAway etc., however they do offer some discounts through us now too since one time usage per year instead every month. This makes things easier because all those fees would be added up each billing cycle otherwise.