This is a game that take some time and dedication to truely enjoy. Yes there are people out there who love to just line up all the peeps into the main area, and just blast them to smitherines. This is fun yes, but this is the playstyle that would lead to reviews of "not having any replay-ability". This is just based on how that person played the game, ignore it, and move on. If you have patience, and a good creativity, make a campain world, and you can prosper. There is sandbox (even for those that are creative it is an amazing outlet) which is like any game's creative mode, allowing infinite building. This has been one of my top five games for most of my life, and will most likely remain there.
Graphics 7/10- While the look of most things is amazing, closer up you can almost taste 2006, but that aside the gameplay it-self is amazing (I personally have not looked into it, but I'm quite sure someone out there made a texture pack or twenty)
Gameplay 10/10- It allows many stories to be played, and can take quite a while (My current time from steam is flawed, I actually have had this game since 2009, and have logged at least 200 hours)
Replayability 9/10- as I said, the game is indeed boring for those without patience or creativity, and I tend to lack in patience, this is my own personal opinion (From any official opinion, I would easily give it a 10/10)
Overall 9.5/10 Amazing game, and a texture pack would put the icing on the cake
For those of you that are the crash and burn kinda people, just letting you know, the peeps are indestructable, believe me I tried VERY hard (Crushing, drowning, melting, more crushing, smashing, throwing, dropping, etc.)
All in all I hope that based on your personal experiences with you own past gaming, you can enjoy this game as well. A excellent use of your $20.