The only problem with the old reputation system was the snowball effect of tenured members. Newcomers, the ones generally being helped, affected an established member's reputation the least out of any member in the forum. Someone who may have consistently been helping out in the Hardware forum wasn't receiving as much reputation as someone cracking jokes in the Social Lounge because established members hang around the Social Lounge and not as much in the Hardware forum. Couple this with the fact that you could give a member negative reputation and you really get a popularity contest.
I wholeheartedly agree with Berry and Lowndsey in that a public display of a person's reputation was better for the forum than worse. To account for the popularity contest, there is an easy fix. Get rid of negative reputation and make the points flat. Each time a member presses "Give reputation" the receiving member gets a point and the comment is displayed to the public. Done.
No public display means newcomers don't know who to trust, etc, etc. All the points have been made really. Stick around long enough and you'll see that there is quite a bit of different opinions on many threads. Enough to the point where discerning between an established member who is legitimately trying to help out and a member who just wants the attention is necessary.