I haven't seen 2 & 3, and I'm not planning to, either. If you look at the stuff that made the first three episodes (4-6) as great as they were, I think it's best not to spoil them by watching 2 or 3.
Like, space ships. In the old days, space ships were rockets or saucers. Plain and simple. And small ones, at that. But who doesn't remember the firs time the Star Destroyer sails along the screen? It kept on going and going. Massive as a whole city! Now THAT is a REAL Star Destoyer! WOW!
And the other space ships were great as well. Not just rockets, but things that looked build and battered, with a definite purpose. That was absolutely a very new way to look at it. While the ships in ep. 1 are just anonymous, smoothed CGI.
As we didn't really had computers at that time, it made sense to have people actually piloting ships, and even manually shooting the guns. Use the force! But let's get real: nowadays nobody believes things like that anymore. Computers rule.
Things like light saber battles stand out in my mind by the duel between Luke and Vader. Vader was such a real Bad Ass. Cool. Cold, even. Almost a robot. He just struts along and... uses that light saber the way it was meant to be used. Nothing flashy about it whatsoever. Chilly, yes. Inhuman? Definitely. Convincing? Absolutely.
But in ep. 1, they first introduce dual bladed light sabers, and have everyone wave them around as if it is a harmless stick. Sigh. It's just a show. Convincing? Not at all. And the baddies wear a stupid mask, and are showmen as well. Bummer.
I want to remember Dark Vader as the ultimate Bad Guy, not as a stupid brat.
Anyway, that is my take on it. YMMV.