Both answers are correct, but the answers are not exhaustive. The Tiger has a reputation of being unreliable, but that doesn't mean it was. This is a good mixture of two logical fallacies: Appleal to tradition and false dilemma.
I voted 'reliable,' based on what I read in Sledgehammers (damned good maps in that book, if I do say so myself! ). The tank itself was reliable. The problem was that they were usually handled abusively (situational dictates), and they failed to receive proper maintenance. Under those conditions, any vehicle will fail.
I was reading 30+ tanks failed in the 160 mile, (250 km) 8th Btn of the 4th Armored relieve of Bastonge. http://www.army.mil/cmh-pg/books/wwii/7-8/7-8_21.htm The state of matériel was much poorer, for there was a shortage of medium tanks throughout the European theater. The division could replace only a few of its actual losses and was short twenty-one Shermans when ordered north; worse, ordnance could not exchange worn and battle-damaged tanks for new. Tanks issued in the United Kingdom in the spring of 1944 were still operating, many of them after several major repair jobs, and all with mileage records beyond named life expectancy. Some could be run only at medium speed. Others had turrets whose electrical traverse no longer functioned and had to be cranked around by hand. Tracks and motors were worn badly: the 8th Tank Battalion alone had thirty-three tanks drop out because of mechanical failure in the 160-mile rush to the Ardennes. But even with battle-weary tanks and a large admixture of green tankers and armored infantry the 4th Armored Division, on its record, could be counted an asset in any operation requiring initiative and battle know-how.