It depends, if you can afford the 2013 go ahead, its faster with nicer screen and higher res. But at the sametime, if you can get the 2012 version for half the price of the 2013 its not bad. As long as you upgrade it to KitKit it will run smoothly. Being a Tegra 3 it can still do a decent job at gaming. Not having a rear camera isn't a lost since you probably won't use a tablet to take photos anyway.
Overall the 2013 version is pretty much better in all area, but the 2012 version is still good value at half the price of the 2013.