I think the most interesting thing I've seen from these leaks are the Portal 2 beta content videos. The temporary time-slow mechanic and the beta voice acting have been really interesting to see. The time slow mechanic in particular could have made the game a lot more accessible to gamers with slow reflexes and refocused the game on the puzzle elements.
> made the game a lot more accessible to gamers with slow reflexes
Just no. A perfect game isn't a game that casts a wide net, a perfect game is a game that satisfies its target audience.