Well, of course four stars. George Lucas' defining work is an entertainment staple, a groundbreaking piece of cinema, a launch pad for not just a franchise but an entire generation of blockbuster filmmaking, and just a plain good time, no matter how many times you've seen it.
Sure, it may look somewhat dated now, but only in the sense that the visuals of a blockbuster today are so expansive that every inch of the screen is filled with detail. In terms of what's actually on the screen in A New Hope, the visuals themselves still hold up. The production design is effective — especially given the budgetary limitations that are now well known. The remastered Blu-ray makes for impressive viewing.
The story (for the moment) is simple in its sweep and straightforward in its details (the evil Galactic Empire are trying to eradicate the rebel forces of good), but larger-than-life in its scale; the Death Star has planet-destroying capabilities, where a death toll in the billions can be brushed aside in the terms of elevated space adventure. (Hey, there are plenty of planets out there!) The notion of the Force is a deft balance of fantasy/mysticism in a world of space technology. It's earnest and effective and lent gravitas by Alec Guinness as Obi-Wan. A New Hope has an exceptionally lean narrative, which makes it easy to jump aboard for the ride.
Meanwhile, the level of imagination evident throughout the production is easy to understate but really shouldn't be. The designs of droids like C-3PO and R2-D2 provide personality and charm to what could've been cold, nuts-and-bolts hardware. The designs of the spaceships are iconic not simply because they were in Star Wars, but because they were impressive in their epic, foreboding scale (star destroyers) or distinctiveness (the Millennium Falcon). And, of course, we have lightsabers. The story's concept of a weapon that's technological but also hearkens back to a more civilized era is an effective building block in the construct of a grander mythology. Granted, A New Hope doesn't have the most dynamic lightsaber duels. (The big face-off between Vader and Obi-Wan looks hilariously quaint compared to the other movies, especially the prequels. But you have to start somewhere.)
The characters are effective archetypes. Harrison Ford as Han Solo is of course funny and awesome in his jaded me-first Han Solo-ness (and his is the very type of personality presence lacking throughout the prequels). Carrie Fisher's Princess Leia is a good female heroine for the movie's late 1970s era; she participates fully in the action even as she's the one being kidnapped and rescued. (I'm still always amused by the fact that she has a British accent for one scene.) And Luke Skywalker is the young kid in us all, earnestly wanting to do good in a galaxy filled with intimidations much larger than himself. As such, his naivete might be his most crucial asset. Mark Hamill's novice performance here can sometimes provoke good-natured laughs, as he seems to be playing a character even younger than he actually is. The droids, as mentioned, are charming and still always make me smile. And Darth Vader is, well, Darth freakin' Vader. His design looks like something straight out of a comic book, providing a visual shorthand for evil. You realize with him, along with many things in the movie, Lucas really took it on faith that something so stylized and elevated would ultimately work so effectively on a big screen in an era when the fantastical was eschewed.
Watching this again recently, I was struck by the effectiveness of the prolonged assault on the Death Star and how well the editing rhythms of that sequence have aged. Lots of actions sequences can feel antiquated after nearly 40 years. This one doesn't. It still feels taut and well-paced, even with the repetition and protraction.
Honestly, any review of Star Wars: A New Hope is pretty much needless at this point. We all know this movie so well. To go into more detail is irrelevant. I'm ticking off the most basic of boxes here for the sake of going on record. But hey — to not be on record for Star Wars seems like an oversight, so consider that fixed.
Special Edition comments: George Lucas takes a lot of flak — and understandably so — for his tinkering with the original trilogy, most of which happened for the 1997 theatrical re-release (although there were still more changes in subsequent DVD and Blu-ray releases). My thoughts on this are probably fairly typical among most fans who are not also die-hard purists. I favor — or at least am not against — most enhancements that either cleaned up the original footage (for example, removing wires that were obvious in certain model shots, like Leia's ship being captured by the star destroyer) or enhanced certain visual effects (like the destruction of Alderaan or the Death Star) or even subtly added new shots that feel like they organically belong (like the CG droid salvage freighter rolling across the Tatooine desert).
I am not in favor of in-your-face shots that add obvious CG creatures (many of the Mos Eisley exteriors) and I could've done without the re-added, previously lost scene with Jabba (digitally inserted over the actor from the original omitted footage) threatening Han, which just seems like a weird deleted extra every time I see it. And, obviously, Greedo shooting first is the epitome of wrong-headed and unnecessary revisionist movie history.