I do hate the crowds that come with Restaurant Week. But the food is what the establishment makes of it, and it doesn't have to be bad. Half the time, it's the worst of what's described here - mass-produced and plated from a bus tub for efficiency.
But the other half of the time, it's treated more as an opportunity for a chef to experiment with unique food that wouldn't ordinarily make the normal menu, and I've had some really creative cuisine at an affordable price.
In what should come as no big surprise, my favorite restaurants ordinarily also tend to also be my favorites during Restaurant Week - places passionate about serving good food ordinarily are more likely to take the opportunity to show off, while mediocre joints treat it more like a Groupon deal week.
This may be colored by my location, Seattle, where reservations are typically not difficult to get except at the very high end during very popular times, even during RW...