When we were backpacking in Ecuador, we met an American who was thoroughly excited to have a future layover at Toronto Pearson. Unsure why, his response was because of the number of sockets available and the fast wifi. I have definitely realized that Pearson in comparison to other airports does have these two luxuries!
The only reason why I won't give it 5 stars is because of the customs line. Compared to other customs in the world, I'd rate Toronto as being highest, up there with Panama City and Kuala Lumpur. Due to the reliance on a machine to process your customs report first, many people aren't used to this system, which causes delays. I would probably consider a Nexus in the future. Although the application process may be long, it's definitely worth the $50 usd for 5 years of short line ups.