I'm going to avoid being redundant because people have already covered most of the bases when it comes to the shoddy employment tactics and climate of the JPMorgan workplace.
However I'd like to offer an anecdote to prove further that they should be avoided.
A very dear friend of mine received a temp to perm position and during the time was an assistant for two people. During a short amount of time (< 6 months), both those people left, leaving him alone, and doing BOTH OF THEIR JOBS. He was run into the ground and offered no extra compensation or retroactive pay when talks progressed between himself, the agency and JPMC. To "remedy" the situation, they offered to hire him at a somewhat decent wage to receive no other bonuses or recognition. Then the BankOne merge occured, he went from doing the work of 2 people to 5+ people because nobody could competently implement an automated system. When something came close, he was assigned other tasks, which mentally stifled him because his original responsibilities were what he enjoyed most. Eventually the move to Brooklyn and downsizing came along and he was laid off. Before he even moved to Brooklyn he was so tired of being used he began his new job search. He's in a much better position now, but it's best you avoid these guys if you want to be appreciated for your work or at least if you don't want to carry a whole department on your back out of nowhere without even a managerial position.