I saw The Lone Ranger and really enjoyed it (and I'm neither easy to please nor a Disney apologist, as some people here know). Some spoiler-free thoughts:
It's no classic by any means, but it's far from "23% on Rotten Tomatoes"-level bad. It's a solid, well-crafted action movie with moments of humor and drama, and comparable in quality to this year's big action/adventure blockbusters. I did have a couple of small complaints (which I'm not going to get into, as it would involve spoiling plot points), but nothing unusual for this type of movie. It's not quite as good as the first Pirates of the Caribbean, but is pretty close -- the characters aren't quite as well fleshed out as the ones in the Pirates franchise, but the action sequences are substantially better. In particular, I thought the climactic sequence was thrilling and well staged, and wraps up the main story on a satisfying note. The audience in my theatre was very engaged (something relatively rare in these parts), and the reaction was notably positive throughout.
After having actually watched the movie, it seems that most of the bad reviews bashed it because it wasn't what the critic thought it should be. There seems to be the expectation that any Western these days has to have some kind of postmodern or ironic slant, or be a sober, gritty drama, to justify its existence. While The Lone Ranger has moments of drama and even some serious historical commentary, what the movie is, by and large, is an action fantasy that happens to be set in the American West.
As such, it is not meant to be wholly accurate in terms of either history or geography -- a surprising number of reviews complained that the movie is filmed in Utah's iconic Monument Valley, and other recognizable settings in Arizona and Colorado, when it's purportedly set in Texas. While all that is true, it's beside the point: the events in the movie (and there is some overlap with actual historical occurrences) are fictional. The setting is used primarily to give color and context to the story. Complaining that The Lone Ranger is "unrealistic" in this way is akin to complaining that the knights and warriors in a medieval fantasy movie speak perfect American English.
Another complaint is that the movie is too violent. I thought it was the epitome of a PG-13 movie -- yes, there is violence, but it is by no means R-rated violence. Critics who complain that the violence in The Lone Ranger pushes into R-rated territory have apparently forgotten just how violent R-rated movies can be -- with explicit decapitations, impalings, disembowelings, etc. TLR doesn't come close. The "problem" with the violence in TLR is the fact that it's mostly of the gunplay kind... I think gun violence has come to be stigmatized as inherently more realistic (and therefore frightening) than, say, swordplay. But the overall level of violence in TLR is comparable to that in a PG-13 fantasy movie, like those in the Lord of the Rings trilogy, or even Harry Potter and the Deathly Hallows. And no, I wouldn't take a 5- or 6-year-old to see any of those movies, either.
As an aside, the problem with critic-aggregator sites like Rotten Tomatoes is the fact that all "negative" reviews essentially count the same, whether the reviewer thinks the movie is an irredeemable piece of trash, or just flawed in some areas. The same is true with "positive" reviews -- they are all counted the same, whether the reviewer thinks the movie is the most sublime piece of art ever created, or just a solid but unremarkable effort. As such, a movie where the overwhelming majority of critics think the movie is just shy of being characterizable as "good" (say, a 59 out of 100) might end up with something like a 20% aggregate score, whereas a movie that's perceived as only slightly better by the overwhelming majority of critics (one that just barely passes muster, say a 61 out of 100) can end up with something like a 95% aggregate score. While the aggregation of a large number of ratings is meant generally to produce an overall ranking that "evens out" anomalous critiques, it doesn't take into the account the "pile on" effect when a movie's negative or positive pre-release buzz (based on something entirely unrelated to the quality of the actual movie, such as its original source material, production company's recent track record, or the prevalent pop culture zeitgeist) encourages critics to be harsher or more lenient than they would otherwise be in a vacuum.
Long story short -- The Lone Ranger isn't perfect. It has its flaws, including some attempts at humor that aren't quite appropriate for the setting. But on the whole, the movie is entertaining, with a few truly stand-out action sequences. It won't be everybody's cup of tea, but most people who generally like action and/or fantasy adventures will find it an enjoyable outing, and worth the admission price.
P.S. One other nit: like many recent action/adventure movies, it's 15-20 minutes longer than it should be. Try not to fill up on the Coke Freestyle machine before going into the theater.