I've watched two TV series starring David Mitchell as the lead actor. The first was Upstart Crow, a comedy set around the time of Shakespeare, in which there were funny moments but, overall, I wasn't bothered about it. I much prefer his story-telling, rants and banter with Lee Mack on 'WILTY'.
The other series, which was the recently aired Ludwig, is described as a 'Comedy drama, Detective, Mystery' - which I did enjoy. Here is a link to the official trailer from the BBC for Ludwig.
I have a couple of books written by David Mitchell. They're a bit exhausting, in my opinion. The short rants that make me smile on TV don't transfer well into long, rambling book form. But, if you appreciate well crafted rants on general topics of life, you really need to visit David Mitchell's Soapbox. Here's an example:
In conclusion, his quick thinking interaction on WILTY (would I lie to you) are top class, his characters on TV can be good but his books are a bit too much for me.