I really liked the nod to the Young Indiana Jones series when he talked about riding with Poncho Villa.
I thought that was kind of neat too. I've been catching up on these as they've been playing sporadically on the History Channel over the past few months, and recognized that as soon as that was mentioned as well. Kind of neat.
Now...back to the movie. I enjoyed it. Not as much as the originals (Raiders and Crusade in particular), but I had a fun time. I will admit that I'm not as hard on movies as many people are, I just go to be entertained more or less. Its also tough for me not to get excited about an Indy movie, because, well, its Indy. When we came out after the movie, I did say to my wife "it feels a little different than the other movies". The alien stuff was a little bit different, and I'm sure likely to draw a lot of criticisms as this movie stays in theaters, but after having some time to let it sit - I don't mind it. It got a little outlandish with the actual alien, the saucer taking off, and all of that - but when I think about it, I guess some of the stuff in the previous movies was outlandish as well. It was just different because of the time frame, and those "macguffins" were maybe a little more well known than the story of the Crystal Skulls. Heck, prior to this movie hooplah beginning a year or so ago, I didn't know anything about them at all really. Then the History Channel and Sci Fi had specials to fill in that info

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As some of you have mentioned, the opening did seem a little slow going to me too. I guess there was plenty going on, but it just seemed like the movie picked up for me once Indy met Mutt on the train platform/soda shop. I actually thought that Mutt (Shia Labeouf) was a good character, and was pretty well acted. Like Jesse mentioned, I think there is some good chemistry there between he and Ford, and its too bad that we likely won't get more of that (unless they really get crackin on a sequel). He was probably my favorite "new addition" to the Indyverse, and I don't have any problem with him being Indy's son. I mean, why wouldn't he have a son? Heck, if you watch the Young Indy chronicles, I'm surprised there isn't more. According to that, Indy was quite the player in his younger days. Anyways, it fit fine for me, and I was fine with the marriage to Marion as well. I think she is fairly well regarded as the "best" of the Indy women, and it makes sense for them to end up together. I know some people will likely not enjoy that part of it as well though.
The one scene that stands out the most to me where I was like "goo", it was the Mutt swinging with the monkeys scene. That was a bit much. I'm not sure why that was in there, other than for a way for him to rejoin the fray. That I could have done without though. Otherwise, I thought the action scenes were pretty good. I guess the overall jungle chase might have gone on a little long, but it did have good parts. I also kind of liked the motorcycle chase earlier in the movie. Anyways, overall, a pretty good movie to me. Probably not quite up to the originals, but with that sort of nostalgia factor at work, its probably hard for it to top them. I'm willing to accept the alien stuff, as its been said since this took place in the 50's ('57), that was what the big thing was at the time: "aliens and other worlds". The Indy movies were always sort of meant to be like the matinee adventure serials, and not necessarily "super realistic", although grounded in realism. I think, for me, its easier to accept and look past stuff like the crystal skull/skeleton/alien stuff and things like Mutt swinging from vines and Indy surviving a nuclear blast in a fridge stand out more to me - I don't know why. As for the characters:
Indy: A+. Harrison Ford is still Indy, no matter what age. I thought he did great, and nothing seemed out of place. Sure, he was older, which is the running gag from everyone these days - but if I can be anywhere near that when I'm 65+, I'd be darn happy. I always enjoy watching Ford, and again he holds that nostalgia because between Han and Indy, I wanted to be him when I was a kid growing up. I think I was Indy for Halloween at least twice

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Mutt Williams (Henry Jones III): A. I thought he was a pretty good character, and had nice chemistry with Ford. Like Jesse mentioned, the scenes with just the two of them were really good. Also, I think Shia is a pretty good actor. I know there is sometimes the tendency to bash anyone "new" or "hot", but I think he might be a case of someone that really does have "it". As for carrying the franchise on, I don't know. It just isn't Indy without Ford, and Ford in the lead I think. Time will tell I guess, but I get the feeling that this is going somewhere (from comments we've seen over the past few months).
Marion: B. Not necessarily a whole lot to do/say, although she was in it a fair amount. It was just nice to see her back in the role. She has aged well too, and just seems to fit in the Indyverse so well.
Irina Spalko: B-. I thought this character was fine. I know some will talk about the Rocky and Bullwinkle-ish Russian accent, but I think that was how it was supposed to be. I saw a review of the movie saying that "its almost supposed to be a little funny", as that was what they were going for a bit. I can deal with that. It didn't really stand out to me too much. Her character was fine, but didn't really seem as "evil" as the Nazis or Thuggees (as was mentioned)
Dovchenko/Russians: B-. They were fine as well. Dovchenko was a good foil for Indy, and it was a nice fight between them. He didn't really have a whole heck of a lot of lines it seemed, but I thought he served the movie fine. Again, the Russians didn't seem as "bad" as the Germans did.
Mac: D. I'll agree with others, I didn't like this character much. I didn't really feel bad at all when he bit it. My wife said to me as we were walking out "I'm glad he got killed off". He wasn't likeable at all, and I'd had sooner seen Sallah back as Indy's partner-in-crime.
Ox: A. He didn't have much to do outside being crazy, but I thought Hurt was very good in the role. I liked the character overall
Overall, I thought the movie was decent - and definitely entertaining. Like I said, not quite on par with the originals, but still enjoyable. I do have a feeling that it will see a "Phantom Menace" like backlash (although not quite as extreme), while making a boatload of money. It just seems that - and I'm not directing this at anyone, because I'm the same way - we're a much pickier and more critical lot of movie-goers than we used to be. The internet has something to do with that, and to be honest, I think the prequel experience does too. There doesn't seem as many people that can just go to a movie and enjoy it, its much more dissected and analyzed now. I still watch movies like I did when I was a kid, to have "fun". Not that I can't see flaws, because I do, but it would be sad to see the Indy "name" get dragged down like Star Wars sort of did in the past 10 years. Its funny with any movie involving an iconic figure/franchise, its like that. Heck, as universally praised as a movie like Batman Begins was (I loved it), you can still see a fair amount of people online criticizing it from time to time. Just the way it is these days I guess.
Oh, forgot to mention this earlier, but I kind of liked hearing Ford utter "I've got a bad feeling about this" in the movie as well. Who's ready to see a 66 year old Han Solo again? (kidding) I remember reading that article a year or two back where Lucas was trying to talk Ford into reprising his Solo role, and Ford essentially said "no way".