"Listen and remember. You are Imperial Guardsmen now. It does not matter to me whether you come from Catachan or Valhalla. I don't care whether you are a volunteer or were rounded up by an enlistment gang. I will teach you to march like Imperial Guardsmen. I will teach you to maintain and fire your lasguns like Imperial Guardsmen. I will teach you to fight like Imperial Guardsmen, and that means learning every dirty trick in the segmentum. Most importantly, I will teach you your duty and you will do it without hesitation, on command. The reason you will do this is because our immortal Lord, the Emperor of Mankind, owns your pitiful lives, and if there is one worthwhile thing you will ever do it is to honour your debt to Him."

WHY PLAY AN IMPERIAL GUARD ARMY
The Space Marines are often referred to as the Sword of the Emperor, a precision instrument to strike into the heart of the Imperium's enemies. If this analogy is fitting, then the likening of the Imperial Guard to a large, blunt sledgehammer is even more so – for the Imperial Guard is seldom, if ever, subtle or swift. Rather, the Imperial Guard is a relentless, implacable machine that will beat down the foes of Mankind in a series of utterly decisive hammer falls. The hammer of the emperor.
The soldiers of the Imperial Guard are but normal men, facing a galaxy of superhuman warriors and lethal alien predators. They rely on superior numbers, disciplined training and above all else, honest human courage. The Imperial Guard is an army that appeals to both the ruthless commander who cares only about achieving his objective and nothing for the lives of his men, and to those heroic generals who wish to see the normal man, armed with only the humble lasgun, prevail against the hordes of bio-engineered aliens and Warp-spawned monstrosities that would otherwise tear the Imperium asunder.
I have always had my eye on the Imperial Guard since first playing Warhammer 40k. The game was introduced to me a while back from a friend, who also collected Imperial Guard. To avoid having the same two armies, I instead collected Tau. While we had a fun time, and most of my fondest memories with that friend are over the tabletop, I eventually sold my Tau army and did not come back to the wargame hobby until recently.

Now that I have, I am coming back to collect, build and play the best damn poor bloody infantry that I can muster.

"To each of us falls a task. And all the Emperor requires of us Guardsmen is that we stand in line, and we die fighting. It is what we do best: we die standing."
- General Sturnn, Commander Cadian 412th
(picture and quotes taken from games-workshop website, the 5th edition Imperial Guard Codex, and the 3rd edition Imperial Guard Codex)