The Filibuster has shown to be effective through out history. Since it helps one side meet its goals then it has to be viewed as a valuable legislative process. I do not think it is a good legislative practice to have and is literally a waste of time, but for as long as people have used it it does get the job done.
Yes, the filibuster is valuable to the legislative process, because it can be used to veto legislation for which there is not a great deal of support. A filibuster can also be used as a publicity stunt, which brings important issues to the public's attention. Either way, the filibuster is a valuable part of history.
If people doing a filibuster are forced to stay on topic and speak about the issue the entire time, then I would be all for it. But for some legislative bodies, you can just read anything meaningless you want. This does not contribute to solving problems, this is obstructive to the process and a wastes of time.