I think he's likeable, but he has a troubled past.
He likes Clara but is obviously a little self conscious and lacking in confidence around women to which he's attracted. Understandable if he was Rupert and grew up in a children's home. Low self esteem. (What happened to his parents?)
Something bad has happened (he probably couldn't save a (female?) civilian? (relative?)) and thinks he's responsible for death(s) (but probably isn't). [He tries to hide his reaction to the "ladykiller" remark, but it obviously made him uncomfortable.]
He's likely to be redeemed by Clara and the Doctor (or find out he wasn't actually responsible). His commanding officer(s) are probably actually responsible for putting him in a situation where he couldn't save everybody hence his dislike of the "officer class". Clara will ride off into the sunset with him and the Doctor will learn not to dislike
all soldiers. He won't be a new long term companion.
My 2 cents, FWIW.
To be continued...