What is the technical advantage of celluloid film over digital?
Film may have better long-term archival stability.
For theatrical exhibition, 35mm film still has a more uniform distribution and exhibition system outside the US and Europe.
People like Chris Nolan prefer to use film because there aren't any widely-available digital processess that can do an IMAX-style presentation, with a huge negative area and screen.  Digital solutions for these exist, but the exhibition systems for these are ad hoc; IMAX on the other hand is a really well-established brand and IMAX screens are everywhere and are a reliable, known quantity.
Digital cinema cameras still have some funny motion artifacts (ahem, Alexa and Panavision) and funny black levels (ahem, RED) that some filmmakers don't like.
Film still has a different look.
Once you're at the highest levels of production, and making studio features, the price difference is really a wash, particularly if you're shooting 3-perf 35mm and doing a DI.