I would say more like a 3.5. The skating rink is pretty small, needed to be zambonied BADLY when we got there so we thought an ice clean was due soon... nope. Definitely took a while.
Otherwise, it's generally not too crowded. They have music playing which makes for a good atmosphere, rentals (can't remember how much) and a small locker room.
It's definitely in a good area, a few minutes walking distance from the Eaton Center in the heart of the city.
Going to check out the rink at the Harbourfront for the first time tonight so we'll see how it measures up. High hopes!