Wheatley's corruption of the centre was well handled as well. From the physical decay to the blue screen error messages (something else that made me laugh), it felt very solid.
The last few chambers were very cleverly designed, combining all of the tools and environmental furniture. It took me a while to work out how to get past the section below, for example, where a number of turrets were sat behind the screen on the right. To get rid of them, I had to drop a load of the blue gel onto the platform they were standing on; this involved catching the gel in light tunnels and manipulating it back and forth until it was overhead.
The final fight took me a few minutes to work out what to do. Wheatley's surprise about me not being dead made me smile. I'm not sure how my character was breathing when I went through the last portal, but the last lift journey was a fitting end.
I just need to find a cooperative partner now ...