He diagnoses well the problems with dating. Encourages intimacy without commitment. Distraction from God and character development. Isolation from friends. Focus on self's physical and emotional desires. Bad way to evaluate future mates.
He also shows a better way. Purity isn't not crossing some physical line, but pursuing righteousness according to God's plan and time, not our desires. Don't shop (date, or otherwise fool around with the emotions of others) until you can buy (commit to marriage). This doesn't mean no contact with the opposite sex, but regulating relationships, so they stay focused outward. Friendships by definition focus on something else. Intimate relationships focus on each other personally, and explore the person.
This topic can be controversial, with everything from parents seeing dating as healthy and a right for their kids, to keeping their kids from talking with the opposite sex of their age at all. Wisdom lies between these two ditches.