Most of the time filibusters are used to hold up decisions and block votes. But some times there are a point to them. Filibusters are really the only time when Congress is forced to listen to what a certain person has to say so in order to get their point across they use the filibuster.
The filibuster is an important part of the Senate's rules. The United States was founded as a representative republic that protects the rights of the minority; even when the majority wants to do certain things. The minority party in the Senate has a right to block votes on legislation that it feels has either not been thoroughly debated enough, or that the legislation might be unfavorable for their constituents. In short, yes, the filibuster does accomplish something important in the Senate: Allowing the minority party's voice to be heard.
Filibusters have been used in American representative politics for a very long time now as the absurdly long and boring speeches that are supposed to present a viewpoint or a protest to a legislature about to pass. It is simply used however to drag out time in order to not accomplish anything. The contents of the filibuster itself are pretty meaningless as both sides already know the premise.
The filibuster is an age-old political technique wherein the person filibustering speaks for an incredibly long amount of time in order to prevent a law or motion to be passed. This is a technique that gets everyone exactly nowhere: it delays the political process and frustrates those who are attempting to vote.