Monte Carlo is a great weapon. Don't believe the lies, those held merit before the patch.
Monte carlo is ridiculously stable for a low impact/high rof Rifle but its impact isn't that low. With aggressive ballistics its suddenly a decent chunk compared to Dr Nope shitfest. While I still find it very reasonable to handle.
Its melee restores almost always after only 2 kills. Sometimes after one. For Hunters this means easy knife throwing for Eris if you fuck up your knife juggler string, or easy blink strikes. For other classes this might even be more useful considering their abilities.
I am not leveling it yet, because I mostly use it against lower level mobs and it does its job at 300, and for Iron Banner I rather use scrub stuff. There is too much on the back burner. But this weapon isn't the shitfest it once was.