I think you guys are forgetting it's not just fanboys of the original trilogy saying you gotta watch the best movies first.
Those are the first movies, and 1,2 and 3 are prequels. They came after the other movies, and even though they're chronologically before the other movies, they're meant to be seen with the original trilogy in mind.
Clever nods, explanations of stuff you saw in the OT...it doesn't mean as much if you watch the prequels first.
Also, watching 4,5,6,1,2,3 is a progression of better special effects and CGI, as well as better and more crazy lightsaber choreography in each movie.
The first Star Wars' lightsaber fight was pretty much crap...two old guys clashing swords. Empire Strikes Back has Vader laying it on pretty hard against Luke...pretty intense. And then Return of the Jedi has a very nice duel between Vader and Luke at the end. Phantom Menace introduced the double-bladed lightsaber and had a huge fight with great choreography. Attack of the Clones had the first lightsaber fight with Yoda, along with an epic battle with tons of Jedi, and Revenge of the Sith's fight with Anakin and Obi Wan was over the top but super intense.
I love the old movies so much more than the new ones, but it is a little depressing to see the drop in technology if you go 1,2,3, and then back down to 4.
Other than the models though...those still look better than most of the CGI in any of the new movies...