I don't understand this item anymore. I feel it is 100% useless. Sure, you revive, then instantly die again... Seriously though, when and on what champions should u buy it on ? Adc buys it, dies, revives, then gets CC'd instantly and dies again. Seems a waste?
it's an item designed to counter divers/assassins.
You are a fed adc in the middle of your team : a zed dives you, dies in the process but kills you : worth.
Now if you have a GA : not worth and you can win the 5v4 afterwards. But if your whole team manage to die while you are waiting for your revival, yeah it's useless :)
I see this item often favored on champs that have easy escapes for when they revive, like Shaco or Akali, who can jump into a 5 man just to take out the adc, die, and then use an ability to get right to safety after the revival. I also see it on tanks like Maokai and poppy, who are extremely hard to kill in teamfights, and when they finally get focused down the extra life can both be extremely helping in letting you continue to tank, or just get you out of the fight all together. Of course it isn't perfect in every situation, or on every champ, but that's every item. they aren't all for everyone, but they all fit someone. Maybe you just don't play the champs it's useful on. Hope this helps though.
I only buy it for the resist.
How about you save Flash for it?
GA is probably overpowered if anything. If you take a champion like 
She is a big damage threat, but the item makes her quite tanky as well with all the resists on top of her constant shielding. The fact that the enemy team has to respond to you as a damage threat and focus you or at least waste important CC on you to save themselves, takes a huge burden off of your team during a team fight.
If they blow a lot of cooldowns to kill you; Your team should have a significant advantage during your 
revive time because now they don't have to deal with the threat of those abilities; In which you then come back into the fight and continue to do work.
Honestly the item can feel almost oppressive on certain champions, especially if they are ahead 
all come to mind where the game feels almost hopeless if they are ahead and have a GA
