When you're eying up a climb, assuming it's a line that's been done before, first and foremost it's worth knowing a couple of things. One: is the climb actually any good? Routes are usually given some form of star rating that tells you the quality of the climbing and the awesomeness of the situations you'll find yourself in.
Two: How difficult is getting up the thing? This is pretty essential knowledge whether you're a beginner or you're an elite climber looking to repeat the feats of the greats. However, with so many different kinds of climbing and a range of grading systems, understanding exactly what something like a 6A+ (5.10b) actually means in practice can be quite a challenge.
