I've been there that time of the year every year for a few years now. It's fine. Yes at mid Vail you'll have to wait on line for 10 minutes, and perhaps that long at other places, but there's plenty of great skiing to be had. If you are a low level intermediate you'll have problems because of the crowds, but if you can ski well you'll be fine. Ideally you'll have a guide, friend, someone to tell you where to go and what to avoid.
Vail is massive, there's plenty of places to go to avoid the crowds, and the runs are long enough that the lift lines can be a welcome break at times.