I think KOTCS is a solid entry in the series.
I had a tepid reaction after my initial viewing, but appreciated it much more the second time around. For example, I didn't like the Doomstown sequence the first time. Indy just struck me as looking ridiculous running around that town, ducking under clotheslines, etc. However, putting it in context, that whole scene was supposed to be surreal and it worked much better for me on the second viewing.
The movie is not Raiders. Raiders was my favorite, and I probably harbored the hope that maybe KOTCS could be as good (my mistake). Raiders had a grittier feel to it with action sequence after action sequence. There was humor, but it was almost incidental to the action. The other movies since Raiders have opted for a slightly lighter feel with more gags.
Also, while the action in Raiders was over the top, you somehow never lost your sense that, just maybe, Indy could have really pulled it off. It just seemed that Indy pursued a given course of action because he was out of options. Could anyone have really pulled off that truck sequence in Raiders? Unlikely, but when Indy starts sliding under the truck it seemed like he was doing the only thing he could at the time.
If you contrast that with the "rubber-tree" sequence in KOTCS when Marion drives off the cliff into the tree that gently bends them to the river below, it just feels somewhat forced. It looked cool, but it felt choreographed, while the Raiders truck chase felt spontaneous.
I thought KOTCS also got a little bogged down in character management. Raiders had two main characters, Indy and Marion, with some classic villians. TOD then had three with Indy, Willie, and Shorty. LC was mostly Indy and his Dad (with Marcus and Sallah along for the ride). In KOTCS we're juggling five characters for last half of the movie - Indy, Mutt, Marion, Mac, and Ox. Action was somewhat sacrificed in order to manage the character relationships. And with that many characters, some of them are inevitably going to end up being a little thin (Mac and Ox in my opinion).
But this is a "lovers" thread, and while I prefer the tone of Raiders, the other sequels retain enough elements that they are undeniably Indy films, including KOTCS.
I loved that they showed the Ark in the warehouse, but Indy didn't see it (although he does in the novelization). It would have been difficult to show it to Indy during that sequence. He was running for his life. Having shown it to the viewer without Indy seeing it was the clever option. Indy will never know how close he was.
I loved the motorcycle chase through New Haven. The second time I watched it, I saw it with my father and he kept pointing out the make and model of all the cars.
I loved how they were respectful of the fact that Indy was older, but that didn't become a drumbeat joke through the whole movie. Mutt cracks a joke, and Indy makes a reference himself, but we don't hear a bunch of corny lines about creaking bones or "I'm getting too old for this". Indy was also not a shell of himself. The action sequences for the most part hold their own with the other movies.
I loved how Marion was brought back to the series. It made perfect sense. You are going to have a love interest for Indy, but the good professor is presumably in his mid-50s. He's not going to pick up some hot young babe, and if he's going to be with someone closer to his age, it only made sense to have a rekindled romance with one of his former flames. Marion was obvious choice because of all their history. I just wish she had been brought into story sooner (in a twist, I thought she could have come to Indy early in the movie and told him that he had a son that had been kidnapped. Basically, I would have switched the timing of her role with Mutt's. That would have re-established her much sooner, and would have made the revitalized romance a little more believable).
I loved the relationship with Mutt and Indy. There was some clever juxtaposition of the Indy / Henry Jones relationship from LC. Even before they find out they are father and son, you sense a growing respect between the two.
So all in all, it was a fun film, and one that can stand beside the other sequels.
By the by, did anyone else think Indy's first line was going to be "Russians! I hate these guys", as opposed to just "Russians!"?