Unless you want pain, don't buy.
I've been a long-term Sonos user and appreciated how well the S1 version worked. I finally decided to upgrade to S2 and bought a new Port direct from Sonos. And it doesn't work. I tried to set it up on a new Sonos network and it decided it needed an update (apparently supplied by Sonos with an out of date version). And it was unable to update. Suggestions online are to update it with the Windows app, but that also can't update. Looks like cheap alternatives may now be more reliable than Sonos.