The mall is at the heart of downtown Toronto and is always busy all year round. They have everything ranging from pharmacies, to a high end food court that uses real plates and cutlery (although I wonder how many forks get stolen every day), and retail stores (of course). There are office buildings above as well so you'll see a mix of shoppers and 9-5 business people in the mall during the weekdays.
The good:
It's always clean and there's a good security presence since a shooting that took place here a few years back. There have been tons of renovation to improve the look of the mall and a few still ongoing. Tons of selection to choose from.
The bad:
Homeless / drunk people frequent the mall (my guess is to window shop). Parking is available but is paid parking (downtown of course). Can get crowded at times.
Overall the Eaton Centre is a mall I visit almost every day as I work and live within walking distance to it. It's a great place to get everything that you need.