The continual updates that happen each month as well as the ability to collaborate without the hassle of file check in / check out of other systems. If there is not a feature currently available it is likely already being worked or feature scripts help to bridge the gap. Cross platform also makes it easy to work on an operating system or even review items on mobile. Review collected by and hosted on G2.com.
The 2D drawing tool could use improvement, specifically it feels like a separate product in that multiple users cannot be in it at the same time. Review collected by and hosted on G2.com.
