The reputation system is great imo except for two things and for some communities the negative reputation is great too and a must. The first issue that should really be fixed ASAP (a patch release would be awesome) is that banned or marked as spam members should instantly have all the reputation they have given out to members revoked but still keep the reputation they have been received, currently they don't so their legacy of trolling reputation is left permanently.

The other is more of a request being that it would be great if there could be actions set to negative reputation levels in the same manner as the warning system works for points, obviously this would be a two edged sword though unless any possible trolls are able to jumped on quickly enough before they are able to abuse it.

What if the user was not banned for trolling but for other reasons? There are many valid reasons to ban someone which do not negate the validity of their ratings.

Reputation based usergroup promotions are awesome to have. It makes community moderation possible and takes out many trolls on my big board. When a user gets less than X reputation points their account gets limited in functionality. When they reach less than X points they get auto-banned. Works great. It would be nice if IPS would include such functionality in the stock software.