This is a classic case of ‘damning with faint praise’. The individual’s component bits just made it to ‘very nice’ but somehow failed to add up to anything other than dullness.
‘It’s difficult to say. I think he’s very nice in all his bits, but rather dull on the whole.’
Source: Elizabeth Gaskell, Wives and Daughters (London: Penguin Classics, 1986 (1866)), p. 658