Well, that depends. The 2000's saw a wild arms race to add CPU-melting watts to gain processor hertz, but the stuff prior to that was actually pretty reasonable. I've got a pile of ISP1100's that idle in the 30-45watt range, depending on configuration, and quite frankly they are going to be able to serve files better than many contemporary NAS appliances. I've got one with two drives in it over there that's idling at 35 watts. The N36L, IIRC, comes in near that withOUT drives.
The primary downside to the N36L seems to be the same as the ISP1100: your bang for buck is not that high. You can burn a small number of watts and get the job done. But you could more efficiently burn a similar number of watts AND run some other virtual machines on a faster (more expensive) platform. I don't know that I'd go running out to pick up an N36L unless I was pretty clear that all I needed was a NAS appliance. But it's pretty darn good at that.