At the opening showing I attended, I saw someone in the lobby dressed in full Indy regalia; it was pretty neat. I jokingly asked him what movie he was there to see, hoping and expecting some humorous response, but he simply said "Indiana Jones," apparently thinking I really didn't guess immediately, which made me wonder whether he thought I was a complete doofus for asking.
There was also a woman in... 'quasi-Indy-esque' garb, not exactly replicating "The Gear" but sporting a fedora and a bunch of generally "adventurous"-looking clothing.
The movie itself garnered an appreciative response from an audience that clearly enjoyed it, though it didn't react with anything near the wild appreciation I recall experiencing with the original Raiders
the first time, all those years ago. It was quite fun all the same, though I found myself wondering how people I knew would react to things like the fridge and all. The biggest and most delightful surprise in the movie (at least for me) was the wedding; for whatever reason I didn't see it coming at all, even though in retrospect it seems like such an obvious thing to expect, and I was thrilled. I heard other people express their delight at this closing moment as well.
The second time I saw it, also on opening day but in a completely different theater and city, the theater's sound was annoyingly muffled-sounding. I was particularly disappointed because I was seeing it with friends who were seeing it for the first time ever, and I wanted them to experience it under better conditions.