No Dropbox, but Skydrive support is built into WP so I've never needed Dropbox.The more I look at the 920, the more I want it. I wish more companies would support WP8... no dropbox, no instagram, no bank app.. is there even a youtube app?
No Instagram... yet. There is (reportedly) an Instagram app being worked on, possibly by MS and/or Nokia.
Banking apps would depend on your bank... mine doesn't have a native WP app, but the mobile web version has almost all the functionality of the app (which I have on the iPad) so I don't miss anything there.
As for YouTube, there is no official app but several very good alternatives (MetroTube is my favorite).