...which you'll already have made your mind up on if you are thinking of buying it in 4k.
Like many films from a few years ago, the 4k transfer doesn't bowl you over in the way that newer stuff can, but it's better than blu ray (in parts, very noticeably). It often seems to me that the bigger benefit for older films is actually HDR rather than 4k, which means that brighter objects are more naturally and realistically bright, such as lighting over the town of Spectre and in the circus. Overall I think it is worth it, as long as your expectations are too high.