There are definent proven benifits to high reps, just as there is for low reps, as long as you know when to use what, you will have half the battle won.
Reps can be an individual thing. I usually have a rep range of 8-12, but at the moment I am doing a program with ranges of 3-5.
I do not agree with jornT statement about PUMP as without pump we do not get a quality stretch of the muscle fascia wich is needed to help alleviate the restrictive tightness on the muscle fibress belly. As long as you are maxing out on your final reps and your intensity is good this should help with a pump.
Some comments just to back up what Turnip is getting at (I think loooo).
Q:Is there any value to a BB doing sets of 20 or more reps?
A:Sets of 20 or more reps are indicated in some instances:
1)Sets of of 20 or more reps work extremely well in certain forms of squats and deadlifts, and, of course, on the leg press high reps can be very effective at creating hypertrophy. These exercises make full use of the stretch-shortening capability of the muscle involved. For example, doing sets of 20 on dumbbell deadlifts is one of the quickest ways to pack pounds on to a lean frame. Studies have also shown that on bench press a load of 70% of maximum will give an individual 12 reps, while at the same % of leg press maximum he or she can perform 40 reps.
20 rep squats were the foundation of many quik-mass-development programs year ago. Entire books cenrered on that methodology have been written, and the system is result-inducing for those willing to work hard.
These exercises train muscles that tend to have a greater portion of lower-threshold fibres than other muscle groups, hence the need for higher reps.
HERE IS THE PART WHERE jorT & Turnip disagree (I think loool)
2)For most trainees hypertrophy comes from repeated efforts of 40-70 seconds under tension per set . Therefore, depending on the range of motion and the tempo at which each rep is executed, sets of 20 can create hypertrophy. Calf training and forearm training are perfect examples.
3)Periodic phases of 20 rep per set let the central nervous system and the joints recover from all the pounding they get from normal workouts. For example, if you just did a 12-week peaking program to achieve new max weights in the front squat and the power clean, doing a few weeks of 20 rep sets will leave you refreshed for a new strenght cycle aiming at personal bests, say, in the power snatch and squat.
High-rep phases don't need to be long. Usually one to three weeks does the trick for most individuals.
4)Another method of using high reps effectively is to conclude each bodypart workout with a 20-rep set. It's a great way to knock off the lower threshold motor units once you've done your quality heavy work. That's a very good plateau buster for hypertrophy training. Make sure you do the back-off set on an exercise that involves a lot of motor units. For example, for triceps the close grip bench press is a much wiser choice than rope pushdowns.
Info came from an article by Charles Poliquin. (so don't bite my head off loool) | 
and yes I just said I go low reps on my current workout have a read and don't be so tense, it is CHARLES who said it not me looool.