Check out this chart: http://charts.woobull.com/bitcoin-nvt-ratio/

"NVT Ratio (Network Value to Transactions Ratio) is similar to the PE Ratio used in equity markets."

The NVT is currently high, but not out of control like it was in 2014. This is the best dataset I've seen for working out if the network is actually being used in a way that matches the valuation, and I think will become invaluable when the CME Bitcoin Futures market opens.