Check out Oklahoma or The Boy From Oz on You Tube. His voice in Les Miz was about a tenth as good as in those. But more than made up for by the sheer fabulousness of his acting.
Agree that Hugh was so good in Oklahoma but disagree about his acting in Les Miserables. I thought that was poor /hammy and over-emotional - sometimes singing should just reveal inner turmoil - not cause emotional incontinence. He also sounded like he had loose false teeth in Valjeans Soliloquy and seemed to suffer from asthma throughout (has no one taught him about breathing). Eddie Redmayne acted better (though I did not like his performance in the TV drama Bird Song) but he just had to do the compulsory teary slobberfest of emotions in Empty Chairs ... but even there he kept hitting the notes right unlike Hugh who in Valjeans Soliloquy had odd accents (from Dundee to Home counties in a line) creeping to try to distract from the ragged singing.