Has anyone experienced this? Reviews? Advice?
I went about 20 years ago, so not sure if it’s changed at all. It was a lot of fun, and there were a ton of activities going on. It’s frigid - unbelievably so - at least when I was there. Dress warm. I’d try to stay in the old town if at all possible so you’re close to all the action. Great food in QC too. They sell (or at least sold when we were there) something called Caribou, which is wine and whiskey I believe. You pour it in empty plastic canes and drink as you walk around. It’s supposed to keep you warm. It hit husband pretty hard, so be careful of that stuff!
We’ve been to Carnaval several times and it’s lots of fun! We love to stay at Auberge Saint-Antoine. Fabulous accomodations, a terrific restaurant, lovely spa, and an excellent location in the old city. Lots of activities to choose from. My advice is to book your accommodation as soon as you can as places fill up early. It’s a popular February destination. 
This sounds really fun! Following.
I love Quebec City, but as @taverngirl suggested, dress warm!!! If you take any bus tours, be prepared to wait in line quite awhile. They were very disorganized last December. My elderly parents from Texas ended up standing outside for way too long - it was so bad that we jettisoned the second half of the tour and got a partial refund. I don’t think I’ve ever been so cold in my life.
Parking was tough and it wasn’t even Carnaval time.
Make dinner reservations before you go, too.
Considering where you now live, that’s saying something!
Standing around waiting for public transportation is what makes one REALLY cold, IME in Chicago and Boston. Here, there is almost none, so not a problem. 