From the article:
When the Tiger was introduced in 1942 it was a weapon un-equalled in performance and protection, there was little the Allies in the Tunisia or Russia could do to knock them out. It had its disadvantages (it was slow and a little unreliable to start with), but at the time its clear advantages outweighed these.
The Production model Henschel Tiger I E had 100mm of front armour on both its hull and turret, 80mm on its rear and sides, and 25mm of top armour. None of the armour was particularly well sloped, but it had lots of it. It 8.8cm gun had already proved itself in combat as a lethal anti-armour weapon.
The first Tigers issued went to the newly assembled men of 502nd Schwere Panzerabteilung, who were quickly sent to the Leningrad front in August 1942. Tigers also made an appearance in North Africa in late 1942, much to the disturbance of the allied soldiers who ran into them, many of the legends surrounding the Tiger spring from these first encounters.
The Tiger underwent couple of upgrades during its life; in July 1943 the cupola was changed to a new design with periscopes and a rotating hatch similar to the Panther. May 1943 saw the introduction of a new engine to improved performance, and in January 1944 a new road wheel was introduced.