The solution's automatic IT asset discovery and inventory functionality are top-notch. The thing I like is that it's open-source. If I need to change them — and they've given me links on GitHub to have them — I can go and change them to pull exactly what I want, as frequently as I want.
The only features that we have found valuable are related to rack elevation and layout, where it has the ability to build rack elevations.
The features that I have found the most useful are the reliability of the system and the simple way to upgrade. They're also moving to a more comfortable user interface.