The thing is that Pritchard has aged, and his voice has lost much of its laddish shine: it is clear that the sound of some of the Kooks' greatest hits, such as "She Moves in Her Own Way" and "Gap" is fully beyond his reach now, and it is unfortunate, for that voice was a large part of what defined The Kooks to the public.
However, Junk of the Heart is still a pretty good single, by virtue of the melody simply being pleasant to listen to, and Pritchard still has enough left in him to bring the chorus to life with the lyrics "I want to make you happy/I wanna make you feel light".
Junk of the Heart is a very good song. It is unfortunate that the rest of the album turned out less than great, but that doesn't mean its titular song isn't worth owning. Recommended.