gotta say, I was really excited when i first switched to my shiny new milwaukee brushless m18 tools, but after using them for 9 months, there are a lot of little annoying things I can't stand..... I use the 1/4" impact a lot and they put the torque controls right under your pinky finger - I often accidentally press the button and change the torque. My 1/4" impact needs to go in for service (it randomly goes the wrong direction for one trigger pull after switching directions sometimes) and that is a LENGTHY process where I won't have my tool. The batteries are WAYY too difficult to pull in and out of the chargers and tools. The wet/dry vac is a nice tool, but the fact you have to open the cover to get to the hose and tools is super annoying - apparently there is an add on external hose holder you can get but I haven't yet. I don't use the onboard bit holders, but they are in really annoying positions IMHO. The brake on the brushless drill is powerful but i feel like the tool is going to break when i'm using a large diameter tool like a 6" hole saw for recessed lights - I bet if i use it on full speed and wasn't careful a few times it would break whatever gears are inside. Also, the last setting on the drill's torque control is hammer drill mode. It's really annoying I can't just quickly spin that thing to max without looking - you have to go all the way and then back one if you aren't looking to get normal drill mode.
1/2" impact and circular saw have been pretty good, but I don't use them much. The only complaint with the saw is that the lockout is too hard to press and akward.