Portal 2 is probably the most genuinely fun game I've ever had the pleasure of playing.
It's hard for me to imagine a plot and environment fitting together more perfectly than Portal 2's. The plot continues off of Portal's plot and I wouldn't recommend playing Portal 2 before you play through Portal. How could they possibly pull something off to make this game's story line just as great as Portal's without degrading it. Well, as usual valve delivered, not only did they match the plot of Portal, they easily surpassed it. Portal is filled with quirky twisted plot all wrapped around a breathtaking and expansive tour through Aperture Science Laboratories.
"Character development", if you can call it that (Self Aware AI Progression?), is amazing. Countless hours must have gone into the perfection of Wheatley, GLaDOS, and Gus Johnson's dialogue. It is both witty and humorous while still maintaining a scifi tone. The little things like detailing, specifically, Ratman's little secret hiding spots, and scribbles on the walls really allow you to immerse yourself into Portal 2. But, the music, the music in Portal 2 is what truly provides the immersion; it literally is the thread that sews the plot and environment together.
I was originally concerned with the games length; how many puzzles can a person do before they become repetitious and boring? In all honesty, probably not too many, thankfully, valve recognized this fact; I truly believe Portal 2 is of perfect length. If it were any shorter or longer it would easily start to diminish the enjoyability of the game. The total game play time in single player for me was 10 hours. This probably seems a bit short for the original release price of $49.99 and I would agree It most likely is but, In this case I would like to stress it is the quality of the experience that matters, not the quantity. (CoD Black Ops is a great example of quantity.) Thankfully this game only costs $30 now and if you watch Steam sales you can nab Portal 2 for under $20.
What a genuinely fun game…go play it you will like it, if not, love it.