I've been on the fence on Ghostbusters. Is the after credit scene worth staying for?
It's "fun," but mileage may vary. It's more of a giggle-esque moment than any sort of integral thing (I think the previous film's mid-credits scene w/Murray & Weaver was a LOT more fun, and the post-credits scene was more sentimental & integral to setting up future stories, as was paid off in the new film).
I'm also on the fence about Ghostbusters as a franchise that seems to have one legit-great first film, and different degrees of "entertaining" with the sequels. To get into the mood for the new movie I did spend time last weekend watching the other Ghostbusters films, and I still may think that Ghostbusters II is the worst sequel, with the reboots being either "fine" or "good-not-great" depending on my mood that day. All have some good moments and legit funny moments, but all the sequels also have their problems.
I do think if they continue this franchise as-is, with similar characters and whatnot, they need to maybe pair down the cast a bit. But that's just me; we'll see how this one does at the box office.