A lot of people here want good/reliable information on the Tiger I, so here is some:
"Armor-piercing rounds usually accounted for half of a Tiger's ammunition supply, the rest taken up with Sprgr. High-explosive rounds for use against enemy soft-skinned vehicles and infantry. The hollow-charge Gr.39HL round, which was less productive at short range, was sometimes exchanged for some of the HE load despite being less accurate. The Pzgr.39 APCBC (Armor Piercing Composite Ballistic Cap) round was capable of piercing 100mm of armour at an angle of 30 degrees within a range of 1000m. The tungsten-cored Pzgr.40 round could easily pierce 171mm of armour at short range and 110mm at 2000m, while the Gr.39HL round could penetrate 90mm of armour up to 2000m. "
"Tiger I was armed with powerful 88mm gun (originally developed from 88mm Flak 36 L/56 gun) that made it a very dangerous opponent for any Allied tank, and its thick (but not shot deflecting) armor made it virtually indestructible. Both Sherman with 76mm gun and T-34/85 stood a chance against Tiger only at close range. It is reported that in July of 1944, commander of 3rd company of schwere Panzer Abteilung 506, Captain Wakker, destroyed Soviet T-34 at the range of 3900 meters. The rule applied by the British concerning the engagement of Tigers was that five Shermans were needed to destroy a single Tiger, but only one Sherman was to return from the engagement. Tiger's only weak spot was its rear armor plate and its engine, which required continuous maintenance. During their combat service, Tigers destroyed large numbers of enemy tanks and other equipment, creating the myth of their invincibility and fearsome power - "Tiger-phobia". Tiger also had tremendous effect on morale of both German and Allied soldiers, German felt secure, while Allies thought that every German tank, especially late model PzKpfw IV was a Tiger ! "...and the T-34s and KVs eliminated hundreds of Tigers...", Russian Newspaper Article about Battle of Kursk, Novosti Press Agency, 1943."
While the second paragraph deals mostly with Tiger VS. American and British tanks there is quite a bit about Tiger VS. Soviet tanks. These two paragraphs seem very pertinent to me with regards to whether the Tiger I was weak or not.
Also, here are some numbers that prove the Tiger was a powerful beast and that the superiority of German tanks to Soviet tanks decreased greatly in 1944 and 45, although this could be attributed to the lack of experienced crews in Germany.
1943:
German Tank Losses: 6,362
Soviet Tank Losses: 22,400
1944:
German Tank Losses: 6,434
Soviet Tank Losses: 16,900
1945:
German Tank Lossses: 7,382
Soviet Tank Losses: 8,700
Total Tiger Losses (includes ALL Tigers): 1,715
Total Tiger Kills (includes ALL Allies): 9,850
For the entire war the Tiger Tanks managed to achieve a 5 to 1 tank kill/loss ratio. Even though this includes Shermans and other "Tiger fodder" this is still an incredible achievement.
Check the 1st of my sources for far more detailed kill/loss ratios for Tigers.
Sources:
http://www.alanhamby.com/losses.html
http://pedg.org/panzer/public/website/tiger.htm