Yeah the abs definetly needs some work... It looks as if it's just one big muscle...
Other than that, great work! Regarding the size of the head, I'd say it depends on what kind of look your going for... If you want him to be a bit cartoonish or in some other way not-photo-realistic, then the head should be a bit big compared to the body IMO...
Other than that, great model so far... The crotch looks a bit odd though, but I haven't done the tut yeah, so maybe it's supposed to look that way...
Liter is French for 'Gimme some ****ing cola before I break vous ****ing lips!"