Answer:
Field Marshall Sir Douglas Haig is widely regarded with very mixed opinion. he was certainly not a military genuis, nor was he completely incompetent. He is archetypical of the "Officer Class" that so dominated the British military structure for hundreds of years, where prestige and priviledge - not skill and leadership - determined who commanded men in battle.
There are some who give him credit for managing the resources of the British and Colonial armies in such a way that made victory possible. Indeed, he was an excellent logistician, and his supply orgnaization was a major factor in ultimate victory. That said, there is a great deal of criticism about his archaic and uninspired methods.
Haig was one who disliked new ideas and tactics, and preferred to stick to full-frontal assaults. He believed a war of attrition was the best way to defeat the enemy, and therefore garnered a reputation for being extremely wasteful of the lives of his soldiers.
Haig rejected the significance of the fledgling notion of aerial power, discounted the machine gun's importance in trench warfare, and had little time for innovative commmanders who came up with flanking and suppressive tactics. He opposed the idea of counter-battery fire (using your own artillery to take out the enemy's field guns) and is widely condemned for repeating failed tactics over and over again in the belief that it was the troops, not the methods, that had failed.
He was considered inflexible, and would often refuse to change plans that were months out-of-date when the enemy disposition had rendered those plans hopeless. He also repeatedly failed to exploit breakthroughs when they occurred because his strategy lacked the flexibility to take advantage of successes in the field.
Haig was one of the last of the world's major military commanders who saw Glory and Honour in the prosecution of a war. Indeed it was, to a large extent, WWI that ultimately revealed the brutality and inhumanity of warfare, and finally dispelled the myth that war was an adventure to which young men should aspire.