At first I was kinda wary of approaching this, as I found Portal to be such an awesome and original game. However my fears were unfounded; the sequal introduces the heroine Chell once again as well as a new cast of characters and some old faves.
The puzzles were great, though some taxed my brain to steaming point. But hey, I actually felt a real accomplishment when I managed to overcome the difficult puzzles and situations.
Exploring more of Aparture and hearing Cave Johnstone was neat, “Science! It isn't about why, it's about why not-” really loved those parts.
The new characters were a lot of fun and I really like talking to them; well them saying stuff to Chell and her giving them the silent treatment. They had such a great deal of character and personality, despite being all machines. Great work on Valve's part, to give robots such appeal, even in MP mode.
Really loved this game, must have!