It’s neither more nor less sinful than smoking a cigarette, cigar, cigarillo, or pipe. I am assuming that you would be smoking tobacco, not cannabis or opium, both of which can also be smoked through a hookah. Be aware that sharing a hookah with others can expose you to additional health risks, principally contracting a disease spread through the mouth (e.g. if you use the same pipe as somebody who has herpes). I wouldn’t do it myself for health reasons, but I’m sure it’s not a sin. I know a monk who smokes cigars, so I assume it’s ok!