I think that shields would not be a very good addition to Minecraft. First of all, we already have swords that basically do exactly what shields would do if they were added: decrease damage taken and occasionally deflect arrows. Second: Would shields negate all damage or heavily reduce it? If they negate damage then that's completely unfair to archers like me who like to keep the enemy at bay when possible, and it's just unfair in general to block all incoming damage. If they reduce damage taken then what's really the point? We have armor and enchants that do that passively, and swords that block damage actively! If shields reduce damage passively then it will become nearly impossible to kill a player with full gear, and if shields work only when the player is using them then shields are just swords that don't deal extra damage! What's the point?
Well, you do have a point, but at the same time, It's called the combat update. Probably Dinnerbone will add a shield button to use the shield while equipped, that's going to rebalance swords because, uh spam click will get beaten when using a shield. Well, even if it would be "unfair" for archers, Remember you get a quiver and differently powered arrows... And I will guess they are going to have potion effects and stuff. Maybe even explosive ones, so the really op thing here will be bows.
Shields would likely protect from frontal attacks, so it's possible that players would no longer be able to pass directly through one another and would collide like how you can push a cow by walking into it, otherwise players would just walk through each other and turn around to attack.
Also un-drawn bow shots would do an amount of damage proportional to their draw-time, minus a small flat amount to account for armor penetration. This would effectively nerf bow-spammers who think that spamming is anything more than just the exploit that is it.
The Meaning of Life, the Universe, and Everything.
The shields have hype because of their potential. They are going to be able to deflect bows,and the enchantments will be good too. DO not forget about customization. What if you were able to customize your shield? And what if you are able to use it like a riot shield in Call Of Duty? You would be able to bash people! that is AWESOME.
Sword Blocking has been lackluster for a long time now. Really its only justifiying value is protecting against explosions and well-timed arrow blocking. However it can't block potions, and the speed drawback is WAAAAY too large for it to be an actual tactic in a fight. A more defensive approach to minecraft combat that involves more tactics and an opening-chance type combat system would be a welcome addition in my eyes.
They honestly should have done this a loooooooong time ago. Especially considering the near-mandatory choice of pvp-enabled servers in this game. For a game that emphasizes so much on the player's freedom to do anything, it's multiplayer does the exact opposite. The vast majority of servers have forced-pvp.
Them adding shields could've made the difference between me quitting this game, and continuing to play it. Guess which choice I made?