It's actually quite good - while it's been failing him a little in the live setting, it seems he's still got it to some extent in the comfort of the studio.
Not to say it's a demanding vocal by any means, but he sounds like himself, whereas when straining while singing '39 these days he tends to take on a more harsh nasaly tone, I've noticed.
I wish I could hear more of Brian singing in that song! Not that I don't like hearing (and watching!) Kerry....I guess it's just something about Brian's (one) voice, I've always noticed...when he's singing backing vocals or something his voice always seems to blend in and be less noticeable....but then again in Queen songs there was often Roger in the mix too, and he pretty much cuts through it all, if you know what I mean :D
Come to think of it, we haven't heard a new Brian-only vocal on a song since uh.....Dream Of Thee? Or am I forgetting something?
'I Do' from Steve Cropper's 'Dedicated' LP in 2011, is the last that I know of.
As to 'One Voice'.....it's 'nice', it's 'OK', but I wouldn't have known he was on it without it being spelled out.
Speaking of which - the 5 Royales are being inducted into the RnR Hall of Fame this year. link