I think the biggest complaint I have is that I'd like to see a choice of graph styles, and perhaps more flexible or even ad-hoc graphing.
For example, when looking at Home>Overview, and having Clients/Usage top-left, I'd like the graph of Clients (by SSID) to be a stacking graph that's filled, like the Usage graph is filled. The same for the Clients/Radio graph when I drill down to a specific AP. I'd also like to be able to have something like a bar graph that would allow me to display a total of all clients by radio, ie 2.4 vs 5. Maybe what I want is available in reporting, but I haven't been able to figure it out yet.
And I don't care for the dashboard graphics on the controllers. For example, the 10 colored boxes for client health and snr. They give no contextual information about magnititue; I need to parse all the numbers in the boxes with my puny human brain. A colored bar graph would be much more useful. And the Traffic Analysis/AppRF Windowy boxes? They are of no use as they are, and it doesn't appear I can change them.