The Al-Khalid tank is meant to counter the acquisition of T-84 and T-90s tanks of India. Its deisel-engine design is meant to be revolutionary which can perform well in extreme heat conditions (as in deserts).
Also its speed and acceleration characteristics make it probably one of the most agile desert tanks in the world as compared to bulky Challenger, Merkava or Arjun tanks.
Hence it is good for countries like Saudi-Arabia, Pakistan etc. which have significant desert terrain.
Since it is cheap, countries like Saudi-Arabia, Malaysia, Egypt etc. which do not have militarily tense relations with neighbours can use them.
However, this tank is like the MiG-21 Bison of the tank community. Features such as light armour, little BMS, lesser crew, medium technology etc. do not qualify it to be a frontline battle-tank for a country like China (it itself refused to use it though it helped in its development).
Even India would not have opted for such a tank as an MBT. But, it is sufficient for Pakistan as it is co-incident with their policy of "minimum detterent".