Here's a few things I notice:
Browsing datastores under the "datastore" view - It would be nice to see all of the VMs in a datastore from this view. Now, I can see the hosts connected to it and get some general metrics on read/write latency, but from this view I can't see what VMs are in that datastore or then see what their performance metrics look like relative to each other within that datastore. It would be nice to have under the "Disk I/O" section (or a separate section) a listing of the VMs in that datastore where you could then see various performance metrics related to storage.
Browsing datastores under the individual host view - On the "Disk" tab it lists the disks by their naa. name. How about changing that display to the volume's datastore name, exactly how it is under the "datastore" view. Or, at least have the option. That way I don't have to jot down the naa to datastore name mapping while I'm troubleshooting or reviewing the data.
Proactive health monitoring - OK, now I'm being greedy...

BTW, I'm not being harsh or trying to find fault. I like this tool! I've been looking at this one along w/ Hyper9 and vFoglight and a few others. Each has their sweet spot, but the things I'm pointing out are the sorts of things that I would use on a daily basis and would find to be material differentiators between products.
Let me know when it's all done and I'll buy a copy.
