i love the first 3 seasons of Prison Break (also in the order you described). i've only seen the 1st episode of the new season, doesn't look that much fun.
imo it had 2 components that really made it fun:
- the sense of urgency in every episode, especially in seasons 1 and 3.
- the company
they are outside now and so the sense of urgency is a bit lost now, while the company is mostly unravelled at this point...