Most critics, especially civilians, underestimated, or were simply clueless about, the importance of speed. Being a wheeled vehicle, the Stryker could run down cars and trucks, something even a fast tracked armored vehicle, like the M-2 Bradley, could not do. In Iraq, where many of the bad guys rolled around in SUVs, the Stryker could keep up. Not only that, but the fast moving Stryker could get to places more quickly, and, in effect, make more "appointments" with the enemy in a day. It's what they call a "force multiplier."
Stealthiness was another thing civilian critics had no clue about. In Iraq, the quiet Stryker could, literally, sneak up on the enemy, especially since so many of the raids are conducted at night. American troops quickly adapted their tactics to take advantage of it, and these stealthy Strykers quickly put fear in the hearts of the enemy.
Much of the criticism aimed at the Stryker had to do with it's vulnerability to enemy fire. In actual practice, this turned out not to be the case. The troops have high praise for the Strykers ability to take hits, and keep on going, or at least protect its passengers.
For older troops who had served in M-2 Bradley mechanized infantry units, it was quickly obvious that the Stryker was a much easier (and less time-consuming) vehicle to maintain and keep going. That meant you had more vehicle ready to roll at any one time. That makes a difference in combat.
And then there were the gadgets. The Stryker was loaded up with communications gear, remote control system , networking stuff and new weapons. Most of it worked, but the young troops, raised on gadgets, found the Stryker an entertaining vehicle to work in. And many of the gadgets made the troops more effective or, failing that, less likely to be bored.
When the Stryker wheeled armored vehicle was introduced three years ago, it promptly became a criticism magnet. The new vehicle was widely derided as misguided and doomed to failure. That's not unusual. There hasn't been a new armored American vehicle in the last three decades that was able to enter service free of savage criticism. The Stryker had one big advantage, as it was able to go off to war as soon as the first Stryker units were formed. Even most critics agree that combat is the final arbiter of which weapons really work, and which don't. The Stryker promptly became enormously popular with its users. What made the Stryker a battlefield success was; speed, stealth, protection, maintainability and gadgets.