Pros
As with most large banks, JPMorgan is very technology focused. The company makes a concerted effort to consistently improve their existing technology solutions, and exhibits a healthy respect for the need for constant improvement. As such, there are always many interesting problems to be solved, and JPMorgan definitely supports employees that are working towards those goals. Additionally, broad common goals are obvious to everyone in the organization, and as a result there is generally good communication across divisions of the firm.
Cons
JPMorgan, like other banks, has a very rigid hierarchy, so its not uncommon to see vast - and unplanned - changes at low levels as the result of fundamental changes further up the ladder (hiring or firing at senior levels). This is an effective way of bringing about change, but often times the resultant changes are poorly thought out or unnecessary. Within the technology side of the bank, everyone is more or less on the same page about roles, responsibilities, goals and requirements. However, outside of the technology groups it becomes apparent that the rest of the bank views all technology costs as simple necessary expenses, and not capital outlays that could generate real revenue. As a result, there is a significant that employees in technology groups are less respected than their business-side counterparts.