W..
No. I have the 16GB 4s and I am already at 7 GB and I've only had it for a couple weeks. I did put my entire itunes on there, so I will start taking off songs I don't listen to frequently once i figure out usage. But that's not taking into account all the pics I will snap in the next couple of weeks.
I can't tell you exact... cuz I'm a work - but some of my apps are HUGE.
I would not get the 8GB.
Now having said that... something is better than nothing. Now that I've had an iPhone I would get an 8GB over anything else in the entire world if it came down to that choice. but I would definitely pay the extra money and go up one size.