One I was on today (yesterday, strictly speaking, since it's past midnight) was pretty much completely full. I think I saw one empty seat in CE, but that's all I noticed.

It had passengers from two other cancelled flights on the same route on the day as well as some from the day before (like myself), so I wasn't surprised that it was completely full. In fact, I think the flight the day before was also completely full because I couldn't even re-book onto it, hence I travelled today instead.