So the shared initiative was done to speed up combat, and it does work.
It wasn't originally part of the game but they wanted to make combat more fluid. I can say it has sped things up a LOT. I think it was also meant as a way to *somewhat* mollify the RTWP crowd, but that's probably secondary.
However, it can cause issues especially if you have impatient players, or a de-synch issue. You end up with two people attacking the same target and not realizing it until the action plays out and or just issues where two different players actions are at cross -purposes.
So I have learned to keep an eye on the Turn bar above and I will always go last if I am grouped on initiative.
As for the de-synch issue - it's a problem with internets mostly.
- Save and Reload if you notice it
- Always have the person with the strongest internets and computer host.
- get google fiber or Verizon Fios.
- Never game over wi-fi, direct connection.
-Clean your computer. Your gaming computer is your holy temple, Thou shall not defile the temple with dirty internet sites. :P
I have about 2,000 hours in multiplayer, so I have seen a good deal of this.