I am not from IISc, but I live nearby IISc. I visited IISc many times during my under graduation. I am doing my M.Tech at IIT Kharagpur.

Before answer this question let me ask you a question .." Do you heard anytime in news papers that IISc students got highest packages??" But you see many times in news that IISc has invented many new things, given many solutions to complex problems etc etc..

If you are thinking of only placements..Then IISc is not a good option. because IISc is mainly research oriented. Studies will be really hectic there, they focus more on deep understanding of a concept. I will give you a one example: Generally in IITs you can do your   project work using some instruments or software's  which are already developed, but IISc will not allow you to use any such tools/software's to do your project, rather than they ask you to develop a tool on your own. you don't even get lot of time to prepare for your placements.

If you are thinking of doing research, IISc is the best option. I can definitely tell you if study in IISc , you will be a expert in your field. But many companies also see other skills rather than only academics, where IISc wont give more importance to extra curricular activities. In IITs you well get involved in many activities.

Packages are not as high as in IITs ( it may vary from 15 lacks to 40 lacks ) I really don't know exact figures.