Should I buy Harman Kardon AVR 3600 for $480

Its a fine deal but HK lacks some of the features of other current receivers.

No internet radio, Pandora, Slacker, Rhapsody, etc streaming

No Airplay for streaming Apple iDevices or Smartphones to receiver.

Lesser room calibration than Denon, Pioneer, Yamaha

Outdated upscaler. Faroudja DCDi video processor isn't as good a offerings from Anchor Bay, Marvell QDEO, Reon HQV ,etc ,

Less HDMI ports, HK only has 4 while others have 6-7 including one on the front panel.

What are you connecting to this receiver? Are they all HDMI devices?

HK sound quality always been good which is one of their strong points.

I've seen several around that price new recently. Last of the close-outs. Rather a good deal for a solid receiver if the feature-set matches your needs. I think all the late ones are HDMI 1.4