Adarsh, ISRO is one of the best Institutes that we have in India for Space Research. It is one of the fulfilling careers anyone can ask of. Working with ISRO can be one's life achievement more even if Stars and Research is their calling. The immense reputation and respect that an individual gets needs a mention here. The only con that we one can think of is that not every day do you launch something and so you put in years of research before a launch. That means immense hours of trials and errors. It might get boring at times. That might be the only con.