I would say it depends on how much of a fan you are of the game.
If you really enjoyed the main-game and want more, then yes i do think it's worth getting.
Off the top of my head the skins you get by buying the jedi temple level: Mace Windu, Qui-Gon Jinn, Sithstalker Starkiller outfit without the helmet on, new training outfit Starkiller, half-man/machine Starkiller(looks really nice, like a badass terminator

), proxy 1 and 2(didn't really care for them but there was a difference between the models.).
There was also a second character pack skins that you had to buy seperate that included: Farmboy Luke Skywalker, Jango fett, Count Dooku,C3PO,3 Starkiller outfits and i'm sure i'm missing one or two but i can't remember the rest.
I didn't buy it cus i got all the characters i wanted from the first pack which was released some time ago.