I did it on a road bike in October last year. A gravel bike would be more comfortably, but it was all well enough surfaced for 25mm tyres.
I did it in a day & a half as my in-laws are just south of Okehampton so stayed there.
It bucketed down & had the headwind from hell on the North coast (you seem to follow the North coast for about 1/4 of the route).
I found the climbs around Petrockstowe the hardest part, I was suffering a lack of calories though as their are a no cafes for quite a distance!
It really is pretty much all downhill from Tavistock to the end, its quite a busy path, even the serious roadies all seemed to have bells on their bikes. Not something I’m used to riding at home in Perthshire.
Dinner & beer at the Barbican, with a dollop of smug satisfaction, are a requirement when you finish.
It was very “type-2” fun for me, mainly due to the weather. I’m hoping to do it in a day next time ☺.
My moving time was 9.5 hours according to Strava, so you could really comfortably do it in 2 or 3 days lugging your own camping kit.