Yes. It's worth it, in my opinion.
The upper rear seat is suprisingly heavy- it has strong metal brackets running all around it. The most weight will be lost from this, along with the spare tire and jack.
Not exact figures here, just my guestimates (I'm shooting low):
Spare tire- 15lbs
Jack- 15lbs
Upper rear seat- 30lbs
Lower rear seat- 10lbs
Trunk panels and padding- 5lbs
Rear speakers/amps- 10lbs
I'm anxious to get back to the track, as I've recently done the above, plus lost my front foglights, swapped out my HEAVY front seats for lightweight Summit seats, removed all carpet from the car, removed the rear dogbone, took off the strut tower brace, and am working on yanking the AC and will remove the spoiler as well. I also have no cats (-20lbs, at least) and no tailpipes (another 15lbs, at least).