If you see a problem that needs correction, the most effective thing to do is often to fix it yourself. This is usually much more effective than complaining about it (see JustCorrectDontPoint).
If you can't fix the problem yourself (because it is too big, or because you have no influence), presenting a realistic plan to those who can fix it is an action that is a lot more effective than complaining.
If your company has serious problems, see ChangeYourOrganization. If your project has serious problems, see HelpYourManager.
You may think you don't have the power or authority to make the necessary changes. But just try it - you may be surprised at how easy it is to effect change. ActBoldly. Even if you don't have a grand plan, you can always FixBrokenWindows.
However, it can be an AlarmBellPhrase if your manager is telling you to do this. I spent several years in a company where I was told this every time I tried to discuss what I thought needed to be changed. When I acted, I couldn't make it happen, and this got pretty soul-destroying. Eventually, I did change my organization, and left, and found it really was the organization, and not me, that couldn't change.
There is an old saying that it is easier to obtain forgiveness than permission.
And in some organizations, that screed is proudly repeated. And it works - until the day comes when permission wasn't sought and forgiveness becomes required - in which case, it often turns out to be the case that permission is easier to obtain than forgiveness. It all depends on how badly you screw up. :)
Complaints are 1) Identification of the problem, and 2) Catharsis. While overuse of this technique can indicate avoidance of actual solutions, this is not necessarily so.
LookForTheDeepReason. Don't just fix problems out of hand. It is better to act than to complain, but a lot of the time it's better to think before acting.
One needs to be sensitive while applying this rule. A lot of turbulence on WikiWiki is caused by deciding to fix problems that are not seen as problems by the rest of the community.
See: ChronicComplainer, StopComplaining, ComplainingAboutComplaining, LeadByExample, CorrectInsteadOfCriticize