I think he's been a bit disingenuous about his nerves ... his hands were shaking like mad at his initial audition and he was saying that for years people have told him he shouldn't bother auditioning for the X-factor as he wasn't good enough (much to the shock of the judges).
But then it turns out that he's sang on cruise ships, which must surely give you some confidence - both in your own talent and dealing with large audiences?
Anyway, as to if he's a nice guy or not, I've no clue. Probably he has his lovely side and his not so great side, just like the rest of us. But I did watch the results on Sunday, and for most of the people who got through, the contestants who were already through and waiting at the side seemed really happy (Jaymi from Union J, I recall, was jumping up and down like a mad thing when the likes of Rylan, Kye etc got through bless him).
When Chris got through, the celebrations seemed a little more 'muted'. Could be nothing, or could be indicative that he may not be as popular as the others.