Hmmm, I have to both agree and disagree with you there. This Indy movie had a very different feel from the other 3, but I still enjoyed the movie very much. You have to admit there were some parts where you said, "Are they really gonna do this?" An example of this is the Attack of The Monkeys, but hey, who doesn't like to see monkeys fight the good fight against Evil Commies anyway? Personally, I like the addition of the Aliens. It's just like The Ark of the Covenant and the Holy Grail, they are both very mysterious and have many theories behind them. Lucas had to choose one theory for the Crystal Skulls and that one happened to be the Extra Tarrestrial Theory. But one thing that did agitate me was that in the Crystal Skull room, if you looked at the floor, they were standing on the Aztec Calender. Now what was the Aztec Calender doing in Peru? Your guess is as good as mine. One of my favorite scenes was when Indy boarded the Freedom Fridge and Happytown blew the hell up and went ZAPPLE DAPPLE DOOM!!!!!! (go to http://www.newgrounds.com/portal/view/442704)
So overall, I would reccomend you watch it in theatres, buy it on it's DVD release, and make best of the Indy merchandise.