Let's play Nostradamus.

#1 - Key Glitch

This one is by far the most prevalent. Each game has 5 Zones, with a door at the end to the next zone. To open the door, you must defeat all enemies in the current Zone. The last enemy is supposed to drop a Key to unlock the door. Sometimes this doesn't happen. EABioware claimed to have fixed this, but instead, it has gotten far, far worse. The only way to resolve this, is for the current host to leave the game, while the remaining members sit through a host migration, restart the Zone from the beginning, and hope that it doesn't happen again. More often than not, you end up with a chain of these, and by the time you get to the end of a game, your entire party is comprised of totally different players than the ones who started the game.

#2 - Red Templar Glitch

Some enemies have Stealth. When you get to the Zone 5 boss fight, sometimes a stealth enemy will go into stealth and stay that way, forever. You can't see him, you can't target him, you have no idea where he even is, anywhere in the entire zone. Oftentimes, you will see his marker on the minimap, and as you are running towards him, the marker will disappear, indicating that he is now stealthed, and you are now screwed.

#3 - Infinite Black Loading Screen

Sometimes joining a game hangs and you get a black loading screen that never goes away, and that you cannot back out of. If on PC, you must alt f4 and start the application again. If on console, you must exit to Dashboard.

#4 - Narnia Doors

You enter the game, none of the geometry loads, you cannot proceed because the path forward does not exist.

#5 - Cannot Move

You enter the game, and you cannot move.

Over the past 48 hours, I have tried to play Dragon Age: Inquision on 4 separate occasions. I kept a list of glitches I encountered.
When I had to leave the game, I will mark it in red.
When someone other than me had to leave, I will mark it in yellow.
When the game completed without issue, I will mark it in green.

ATTEMPT 1:
Game 1: Key Bug, host left
Game 2: Key Bug, host left
Game 3: Key Bug, host left
------ Key Bug 2nd time, I was host, had to leave
Game 4: Can't move, had to leave
Game 5: Ok

ATTEMPT 2:
Game 1: Key Bug, host left
------ Key Bug 2nd time, I was host, had to leave
Game 2: Key Bug, host left
------ Key Bug 2nd time, I was host, had to leave
Game 3: Infinite Black Loading Screen, exit to Dashboard
Game 4: Can't move, exit to Dashboard
Game 5: Ok
Game 6: Ok
Game 7: Infinite Black Loading Screen, exit to Dashboard

ATTEMPT 3:
Game 1: Key Bug, host left
------ Zone 5 Boss Fight Stealth Troll Mob, I was host, had to leave
Game 2: Played something else (this doesn't really count but eh)

ATTEMPT 4:
Game 1: Key Bug, host left
------ Key Bug 2nd time, host left
------ Key Bug 3rd time, I was host, had to leave

Out of 15 attempted games (not including the "Play something else"), 3 of them completed without issue. That's 20%. 80% of the games resulted in game-breaking glitches that forced players to drop out. In 15 attempted games, 17 players had to quit. That's more than a 1:1 ratio. Whenever a game of Dragon Age MultiPlayer begins, there is an astronomically high probability that someone will be forced to drop out with a game-breaking bug.