Intelligence affects the Science, Repair and Medicine skills. The higher your Intelligence, the more Skill Points you’ll be able to distribute when you level up.

“A smart cowboy’s good at most anything, from suckin’ the poison out of your rattler bit to fixin’ your broken wagon axle.”

Intelligence is again a solid attribute… and even though it has been reduced in potency, the fact remains that a character with higher Intelligence will have higher skills, which does all kinds of good things. Not only will you pass more [Intelligence] checks, but more skills means you’ll pass more skill checks, too, and in New Vegas, there are a lot of them. Simply put, a more Intelligent character is a more versatile, stronger character. And yes, half-points do carry over to next level, so with a 9 Intelligence, you’d get 16 skill points to distribute on one level, and 17 on the next. With all the new DLCs, Intelligence has become somewhat less useful. Sure, with more levels you stand to gain more benefit from each point of Intelligence… but there are so many new levels, so many new books, that you just don’t need as much Intelligence to max out all your skills. Having a high Intelligence is still nice for some dialogue options… but it’s nothing a well-timed Mentat can’t get you.

Start out with six Intelligence. Your first priority in Fallout: New Vegas should be to get the Intelligence Implant from the New Vegas Medical Clinic to ensure you’re gaining as many skill points per level as possible… hence the “New Vegas Medical Clinic Run” section. Again, you don’t need quite as much Intelligence with the expansions installed, so an end total of seven is more than enough.