quicksilver is like a cheap verison of flash.
Quicksilver has been the most well thought-out speedster for a long time. DC just threw together everything someone could do at high speeds into one character and had him protected from the drawbacks of it by a mysterious "Speed Force".
Quicksilver's powers are fully explained as are the drawbacks of his powers. Dodging bullets, running at high speeds, thinking faster than computers. It's all explained: Why he can do it, how he does it and how he copes with it.