All your pictures, videos and files will be in the iCloud. It's quite difficult to get them out of the Apple ecosystem into the windows/google universe (unless there's an easy way to do it I don't know of). It's very much easier if you use Macs rather than Windows PCs.
The browser, Safari, will seem strange and primitive.
After many years, I still find iTunes to be a very unintuitive and poorly designed piece of software.