Shoot me straight - how friggin long did it take those of you who have it to get it?  And how did you do it, any particular match modes that yield more exp?  I'm pretty good at the multiplayer (level 14 in about 3 sittings) but for the love of god that's a lot of EXP
 
I flipped through a few pages and didn't see a topic on this pain in the ass achievement, so here it is.

I'm at level 37 and I've played 15 hours so I'm guessing around 20-25 hours to hit max.

Manhunt is what I played a lot. It helps if you cycle your abilities instead of using the same one over and over again so you can complete different challenges and get their xp awards. Honestly 1-45 was surprisingly quick. It wasn't until 45-50 that I felt it started to slow down a little bit.

Thanks dudes!