Very fun and addictive, but can get boring after too long. In this case repetition is not key.
The game play is really fun, and first time finishing it will definitely be great fun. but when you play through it with another character, chances are you're going to have to go through the same missions over and over again.
Every character has their own little cut scenes through various parts of the game but the biggest problem with this is sometimes when you're using a character that bares any relevance to another character they share the same cut scenes. The least that could have been done here is make it a little more personally reflected so you can actually get some insight as to what they're thinking, rather than just tossing in a video from another characters story into someone else's story.
In order to unlock characters in the game, you have to finish the story of a character that is relevant, so you're bound to come across this blunt repetition if you have any plans of unlocking all the characters.
Despite all these things that are a definite turn off, the game is highly addictive and you may very well, surprisingly enough, find yourself returning to it until you unlock everything.
as far as Cost vs. Enjoyment, its money well spent.