I've played more multiplayer than campaign at this point. It's strange, but I have much higher level loot in multi than in campaign. I like that you can sit down and play a match that lasts about 20 minutes, if your group is good and make it through all waves, you get more gold. It works well with randoms or friends, the matchmaking is good in case you don't have 3 friends.
The concept of using gold to buy chests isn't new if you remember the loot in mass effect 3, it's just like it. My strategy is to save up enough gold through matches to buy the biggest loot chest for 1200g, rinse and repeat. At first I was put off by the loot grind like most people. I was getting level 5 gear white and blue items and had played a LOT, like 10+ hours into it, my characters were like level 18 and this loot was only level 5. Eventually I did start to see higher level stuff, and noone knows for sure, but i suspect it starts upping your item level discovery after you prestige your characters. Maybe it just took a lot of duds before I saw good loot coming out of those chests or maybe it raises the quality of loot if you pay real $ for chests? Only Bioware knows! Now that I have prestiged 3 characters I am regularly finding level 20 items, level 22 items (highest level at the moment) and epic items (I still haven't found a levl 22 epic item).
The loot truly determines the strength of your character in multiplayer more than anything though. You can be level 3 and wear the same loot as a level 20. Your loot stays persistent when you prestige. The highest level of play is just popping open more loot chests between matches, eventually you find unique purple loot, some of which gives your characters entirely new abilities. The best unique I have found so far is a staff that has a % chance to apply living bomb. Since I can equip that staff on any of my mages, I can essentially give any of them walking bomb, but the necromancer class is usually the only class that has the spell. It's an interesting wrinkle, and I'm looking forward to finding more of them.