Although I mainly use iWeb, I upgraded to iLife '09 for the improvements in iPhoto and I have no complaints.
iWeb has been dumbed down, has no user requested features added and the new FTP is causing havoc!
If you are into building websites, you may be better to stick with '08 until Apple gets its act together or, preferably, a new development team for iWeb.
I don't do movies so I can't comment about this.
My thing is music. I wouldn't consider using GarageBand nor would I recommend it to anybody except, maybe, those who know absolutely nothing about recording.
The integration of the iLife applications is useful for me, occasionally, for using between iPhoto and iWeb. The ability to pull music files from iTunes is not.
I detest iTunes and have "ordered" it not to launch under any circumstances.
The concept of iLife is great - the implementation is not so good.
If you use a least two of the applications is good value for money.