With all the data open you see some funny things. My favorite is how often I get packet loss IN, but never get packet loss out.
Also, with the graph open, you can see how broken consoles are. You can watch all your hits register on your end, then suddenly get deleted on the server side when it has decided you died, then you ACTUALLY die, then the console damage actually pops up on the graph magically. Great stuff.
Personally though I find the data generally useless because there's nothing I can do about server side lag except see that it isn't me that is the problem. "But we fixed the netcode" blah blah blah, yea, sure.