I have booth classic Spider-Man Omnis, which starts with Amazing Fantasy 15 and go up until #67
The problem is, that the first issues are unreadable today. I like some parts like the first Issue of Amazing (Have a Reprint Issue of this one, its, one of my biggest treasures), Doc Ocks first appearence, but most stuff is far to corny. So I am stucked about issue 10,11,12 and cant get myself to read further.
But I know that when John Romita Sr. joins the series, things will be much better and its going to be readable again. There are a couple of stories I really like, like Spider-Man No More or the first appearence of King Pin.
I really hope, we get a Vol. 3 at some point.
After this, the reprinted stuff is very selected. They offer the important stuff like Death of the Stacys, etc., but there is tons of stuff missing until the clone saga stars, from which is as good as everything is avaible (Partly to insane prices, Marvel needs to Reprint some of the Clone Saga Epics ASAP!).
When you plan reading the old Spidey stuff, you have to keep in mind, that the comics are corny as hell. I think its interesting from a historic perspective, but when I were not the Spideyfanboy I am, I would skip it and start when Romita joins the party and read until Conway leaves and then skip forward to Stern and then Michelinies Run.