The Kritzkreig is very different from the original medigun. It differs from the medigun because it lacks the ten seconds of invulnerability that you normally get however it charge 25% quicker and you get ten seconds of crits. Consequently a different play style is needed. It is important to get into the habit of letting rip a kritz because it is better to partially use than to drop it completely.
The main disadvantage of using the kritz is that even when you pop it you are still vulnerable. This means that you cannot rush into the enemy without looking around and being prepared to retreat if you are likely to be overwhelmed. When you are running the kritz you have to be more aware of scouts especially when you are using the kritz as you can still be killed.
Advantages of the Kritzkreig
@The kritzkeig can clear a whole room of enemies if used properly.
@It only takes 30 seconds to get a full uber compared to then 40 seconds of a normal uber, this means that you can have an uber advantage.
@It is strong on defence because you will encounter less sentries
Disadvantages of the Kritzkreig
@Useless against sentries
It is highly unlikely that you will have a scout near you as they are normally on the flanks. However if you do then they can be a good target for you kritz as their pistol is extremely rapid firing and it can be reloaded really quickly, this makes more use of the ten seconds of crits.
The soldier is a good choice as the crockets are usually one shot kills. But it is a good idea to switch to another person when you see him reloading. If you can find a good demoman then you should switch to them.
The pyro isn’t the best uberee because they have to get in really close to do any damage and because any observant enemy will spot you and kill/push you away you have to try to ambush them.
A good demo can be a good choice because crit direct pipes can be devastating, so can stickies although it can be hard to hit people escpecially if they have space to run away. This is best used if they enemies are trapped in a building or are defending a confined area.
At close range this is the best uber target you can get because he does not have to reload and assuming he has full ammo he will not run out in ten seconds. However at long range he will not have a chance because he is vulnerable to snipers an soldiers.
Engineer, Medic, Sniper and Spy
Although they are unlikely targets if you are desperate they can be valid targets. The engineers pistol can be very effective dues to it quick firing and reloading speed and the aamount of ammo available. The sniper can crit bodyshot people which can be a one shot kill on the lighter classes such as scouts and engineers.