its oled, they changed the hinge mechanism (now it runs down the WHOLE back instead of just a tiny one) its a little more power hungry display, but the system was tweaked to have the same battery life as the smaller switch, they doubled the internal storage, they added a lan port to the stand (which was an extra 20-30 without it, afaik) and it works with all your same peripherals. Some people have guessed that the speakers might have a slight upgrade. it costs $50 more than the regular one.

here's an archived pic of the new hinge

it's not very heavy when you're gamin on it, it feels about the same as the big xbox controller for the ogbox, but with better ergonomics with the smaller form factor. actually it might be closer to the weight of a 360 controller, I havent consolled in a while. it's pretty effortless to game on. but if youre only going to use the tv, yes, just get an old one and never unplug it. the benefits there are the new dock's built in lan, and the doubled memory if you download a lot of games. the other upgrades are mostly helpful for mobile play.

There are also a few brands of controllers you can use for the plugged in mode.