I should start by saying that in Southern Ontario just about anywhere you go you can expect it to be busy. Blue Mountain however goes above and beyond this... From my visits there are always way more people at the resort than the hill can actually handle. The lift tickets are rather pricey for what you get(56 dollars for the day when I went). I did not have to rent, but people I was with did and the rates were high(38 dollars for a day).
The hill itself is alright at best, I found the hill to be really chopped up and wasn't expecting this at all. I didn't find any of the runs to be terribly challenging, but there is a good variety.
In summary Blue Mountain is an alright resort if you don't have any other options. Contrary to what many people think, it is not actually the biggest hill in Ontario, so don't believe everything you read.
For anyone in Southern Ontario looking for the absolute best skiing/snowboarding you can find in the province... head up north to Sault Ste. Marie if you have the time. You will not be disappointed as Searchmont provides basically everything Blue Mountain doesn't... cheap lift tickets, non-existant lines, the best hill you can ski/snowboard in the province AND its bigger than Blue Mountain.