We may all be judging this too quickly, after all, we don't even know how this Doctor's personality is going to present itself. Will he be serious and glum, or fun and playfull? Will that suit the outfit, or serve to add to the quirkiness of the Doctor by being different to what the outfit suggests? Also (assuming Capaldi has a long run) there's time for him to add to/change the outfit. Tennant kept changing ties and shirts, and then got a different suit, Smith radically changed from tweedy Don, to Victorian sulky. Going further back, Pertwee changed clothes all the time. So this could be just the first iteration of 12's look.
I still maintain it's more 'clothes' than 'costume' and I doubt it's going to be many people's first choice for cosplaying, but I'll wait and see. I'm just hoping the new Doctor means fresher story ideas.