It is a "mandatory" place for locals to take their out-of-town visitors; when I was there at least three groups were a mix of locals and their guests. It is cool to see two countries and two states. Countries USA and Mexico; States Texas, New Mexico and Chihuahua.
Go early (opens at noon) the trip up is 4 minutes, and figure another 15-20 minutes on top, then 4 minutes back down. If you wait too long, you will stand in line longer than going up there. Having said that, depending upon time of year, closer to sunset would yield some nice snap shots.