I think he's the best Doctor since Patrick Troughton, perhaps around the same level as Tom Baker.
But they just aren't serving him well with the scripts he deserves.
It's just such a waste.
It's so frustrating. The vast majority of stories aren't necessarily bad episodes, it's just that the stories don't engage as stories. The stories for the most part are as if they are merely throwaway means to an end.
I want to be involved in the stories, not told at the end of each episode "Oh the story didn't matter, it was just a load of fun nonsense to serve some fancy high concept tricksy thing we wanted to do".
The stories now just feel like they are tricks played on the viewer. What I mean by that is that we perhaps settle down hoping to watch a good story played out, but to then find out that the main story itself was just a MacGuffin, and what we were tricked into caring about was meaningless really as the series arc was what was more important.
Now each episode feels like the story is just a bit of mucking about for a bit to serve as a means to get to the end scene of the episode.
I'm going OT a bit, but I'm just trying to emphasise the point that it is vital that they write some bloody good stories for Peter Capaldi's Doctor before he leaves and his potential is never realised.