I don't like prison shows. No matter how many people told me that Oz was great, there was no way I was going to sit in for the unending misery of Nazi cliques and regular rape. Sorry. Also, frankly I'm a bit tired of conspiracy shows. I couldn't stand the X-Files or Alias. There have already been far too many shows where a mysterious conclave decides how our world works.
Why the hell do I watch Prison Break, then?
For one thing, the main character is fun. For those of you who don't know (this was all revealed in the pilot, so I feel spoilers are ok), Michael Scofield has a plan to break his brother, on death row but innocent, out of jail. First step: be the guy who designed the jail, and have the blueprints encoded into a full upper-body tattoo that you get before going inside. Second step: work out "every detail, every contingency". Third step: get yourself into jail by committing a violent crime and requesting your brother's prison in particular to serve your time in.
The greatest part about the show is that you know he's going to make it work. Scofield is not a character---he's a superhero with an intricate plan. Every episode part of the plan is revealed. He's cool, calm, and sure of himself.
That said, this show is made pretty lousy by a cast of unnecessary peripheral characters. Lincoln (Scofield's brother) has an ex-girlfriend who is trying to unravel how Lincoln was framed for the murder of the Vice President's brother (this is where the conspiracy comes in). The actress is whiny, and the plot development is worthless. Just wait until they break out and let Scofield solve the crime!
Also, there are way too many scenes with Lincoln's son, wife, and her suitor. "My daddy is in jail! You don't love me! This guy you're with is a jerk!".
So, this show is mostly watchable if one has something else to do during those ignorable scenes. But the break itself is rather marvelous.