When you drive it alot and really gain some experience in it, killing things is easy.
And, yes the armour is very good when you know how to park it and angle hits.
1. Park behind a hill and only expose the turret front.
2. When a round is shot at range, you have enough time to turn the turret to an angle and cause a ricochet.
3. In a normal fight where your lower hull armour is exposed park at an angle with the corner of hull pointed at the enemy, this will cause most oncoming shots (Except that of higher caliber guns such as the Tigers 8.8cm/ Firefly's 17lbr) to ricochet off the tank.
#4 AND THE MOST IMPORTANT RULE:
Get to know it before you start trying to take on Tigers and Panthers, know your gun and armour.
As well as Armour penetration of the 75 M3 at ALL Range's.
You could say this, "Become part of the tank"!