Sounds like it may not work that well in hotels, assuming it has to go through the network.
The hotel wifi security might well prevent the dongle from being discoverable on the network. Then, if you can only play internet content, not local content from your device, the connection might well be too slow.
What I would like to see if a dongle that same size that acts as a DLNA renderer. Then you could stream content from your device to the TV, but there would still be the wifi security issue.