In an open environment where speed is needed then you will hardly find a better vehicle...It's good for raids and quickly transporting troops on the battefield.
On the other hand it can easily be taken out by just about any weapons system. It's only good for fighting against lightly armed opponents, and its effectiveness and mobility can be mitigated by roadside bombs.
If you can manage to keep them out of cities agaisnt an even moderately armed opponent, then you'll probably have some success with them. There is a saying among motorized/mechanized forces in the US Army..."If you can't truck it...F*ck it!" Having a vehicle to carry ammo and supplies is nice to have so that the dismounts don't have to carry them. With that being said, if one uses the truck in this way then the entire truck becomes a platform from which to fight from. The implications are that the dismounts are tied to that vehicle, you take out the vehicle, you effectively take out the team operating from it.
Put them against anything resembling a modern army or even a force with a few AFVs and they will quickly go by the wayside. I had a 1SG during the invasion who summed it up rather nicely...Technicals were being used to fight against our forces as we moved towards Baghdad. He had us go by one of the technicals that we destroyed to look at the dead occupants inside. He stated "gentleman, don't be like these guys, don't die dumb. They were outranged, out gunned, out armoured, and outclassed...this is what will happen to you if you lose your mind over here." The point was driven home abrubtly with that statement.