The short answer is: No, it is not the same crappy weapon we sent to Vietnam.
We can still argue about whether .223 / 5.56mm is the best round for use in combat or whether a heavier cartridge would be better, but the reliability and QA/QC problems of that weapons system have been addressed and it is a reliable and sound firearm.
From what I understand the 5.56 mm was good in Iraq where one saw lots of urban warfare but in the wide open spaces of Afghanistan the heavier cartridge is better.
223 / 5.56mm
In every state I am familiar with its too small for deer hunting.It is considered too small for a humane kill.
I call it a rodent gun or something suitable for training kids and girls.