Its pretty much on par with the previous two sequels. Trust me, its not a prequel thing, it has good acting and decent writing and its a fun adventure, people just hoped it would be "great", but none of the original sequels are "great" in that sense either, but they are still considered great simply due to time and growing up with them. Like I said, I imagine if I was around for Temple of Doom my first reaction would be "better than most sequels, but you can't expect it to be better than Raiders," which is not a prequel-esque deluding myself into liking it type of excuse, you just need time to step back, have some perspective and watch it again. Thats my impression of Crystal Skull. I honestly don't think its really that much worse than the two sequels, I'd say its the weakest of the three in my personal opinion, but the difference is kind of negligable. T2, Aliens , ESB and Godfather II are all total anomolies, its totally unrealistic to expect or hope for that in any movie but when they happen you're thankful that somehow they improved upon the original, but I can't say that Indiana Jones series was an example of this either, they were just consistently entertaining films like Back to the Future trilogy, which has "average" sequels to a "great" original, but over time looking back we consider them all classics even when most series (Rocky, Jaws, etc) aren't, because those other series weren't consistently entertaining the way BTTF was. Indiana Jones was this way like BTTF and Crystal Skull is no exception, in my opinion. Like I said, its difficult to look at it from this perspective because this perspective requires time, which we have not yet had.