I would say life changes more after joining IIM Ahmedabad than after graduating from it. The academic workload, strenuous hours, assignments and exams all prepare you for the hectic life ahead. So once you graduate from IIM Ahmedabad you might even welcome the hectic work schedule with amazing salaries. The changes in your life will depend on the field you have chosen.
If you join a big consulting firm or an investment bank or a PE/VC, chances are you will spend more hours in your office than at home.
If you go for a general management role, your life will have a blend of both work and personal time.
If you join a technical firm, then you will experience a casual work culture and a lot of personal time.
Working at e-commerce giants and start ups will limit your chances of a work life balance.
As far as the pay of an IIM Ahmedabad pass out is considered, literally everyone gets paid decently. In fact after a few years you will focus more on your responsibilities than your salary. You have to carry the weight of being an IIM Ahmedabad passout as everyone will have high expectations from you.