Well, in the preface to the second edition, Apostol writes:
"The second edition differs from the first in many respects. Point set topology is developed in the setting of metric spaces as well as in Euclidean n-space, and two new chapters have been added on Lebesgue integration. The material on line integrals, vector analysis, and surface integrals has been deleted. The order of some chapters has been rearranged, many section having been completely rewritten, and several new excercises have been added."
I have not read the first edition, I've read parts of the second, so I can't comment. I do agree that when a book becomes popular, the price becomes bloated.