I suppose this review might be a long time in coming (especially after giving a hint about it), so I might as well speak my mind about Portal 2.
As the sequel to perhaps the best loved game (backwards or forwards), Portal 2 has most of the trappings that one could expect from it. More interesting portal and physics based puzzles are contained within.
The only thing wrong with it that I can think of
are the characters is Wheatley.
This thing is a complete blabbermouth. There I am trying to navigate around a maze of death, trying to focus, and he just has to say something stupid. In the first, GLaDOS would only speak at the beginning and ends of chambers, for the most part. Wheatley follows you around for a significant time of the game, always saying some thing or other. Over-dramatized I say, and he got what he deserved.
The multiplayer coop is a nice touch. Played it and finished over a month or so. I recall that I solved one rather involved coop chamber while my partner was AFK. It involved standing and putting things on the top edges of columns and flinging around the air.
I have most of the achievements unlocked (75%). Some happened naturally over the game because I take the scenic route (Door Prize, Ship Overboard) or because I have a slight tendency to fail (Good Listener). Others I looked up (Final Transmission) and even got a slippery one after a few quickloads (Schrodinger's Catch).
This "Perpetual Testing Initiative" sounds interesting. I tried Portal: Prelude with the first Portal, but found it ridiculously difficult, it gave me a headache, and extremely claustrophobic (no space to think). Let's see what happens...