25ms response (very typical now, faster ones are available too) means refresh equivalent to around 40 frames/sec. Games generally do 30 or less.

The other thing to keep in mind is that 25ms is a worst case scenario of how long it takes to go from black to white then back to black. The number is actually two numbers togther, the rise time, ie how hong it takes to go from black to white, then the fall time, or how long it takes to go from white to black. My personal LCD has a rise time of 15ms and a fall time of 10ms.

In games, how often is the screen actually making such drastic changes? Not that often. So, a 25ms panel actually is pretty decent for gaming, with new panels hovering around 15ms being pretty much perfect.