Eh, costumes for the Doctor generally trend toward “silly.” I mean, look at Tom Baker’s mile-long scarf, Peter Davison’s decorative celery and cricket outfit, Colin Baker’s…everything, Sylvester McCoy’s umbrella and question mark sweater-vest, et cetera.

Granted, new series Doctors have been a bit less “silly” (unless you consider Matt Smith’s tweed, suspenders, and bow tie silly) outside of Capaldi’s frequent hoodie and frock coat combination, and even that was a bit understated compared to, say, Jon Pertwee’s frills and velvet.

Having said all that, I think Whittaker’s costume is a little bland for me, but there’s a big difference between promo pictures and seeing it in action - just look at how Capaldi’s costume(s) turned out during his run compared to the reveal promos.