I had the dewalt battery power wet/dry vac. Used it maybe 20 times for the 8 months that I owned it. Being able to carry it around and not dealing with a cord was great, but it lacked power, specially for carpet clean up in a car, also it was pretty noisy and loud. YouTube review shows milwaukee having that power, but also being a battery hog. Now that I got some 9.0 batteries I might pull the trigger...just waiting on a deal.
What's nice too is the vac accepts standard accessories. I have one of those small brush attachmens that I use with mine alot. Helps getting some stuck on dirt and dust off..
At least your willing to get yours dirty

And a lot of us have been waiting to know!
Ok fella's just did a test. I hate you guys for pressuring me into the test and getting the new M18 dyson like vac dirty because I now regret buying it!
Test summary - Cleaned the filter on the M18 wet/dry vac, lets say it was 90% efficient. Used a XC 4.0 on both vacs. Performed various test on my carpeted basement stairwell which was disgusting.
I used the new M18 vac first, it seemed to be doing the job but was not blown away with its performance. Fired up the trusty wet/dry one and it was noticeably better. Sure its a lot louder but who cares, vacs are suppose to be loud and reducing the sound almost always results in less power. There was a stuck lint ball on the carpet, 4 hits with the new one and it was still there, 2 hits with the wet/dry and it was sucked up.
So the new one comes with lots of attachments which was a selling point for me. But whenever any attachment is on the unit nozzle or the hose nozzle, with moderate force they pop off WTF. Oh BTW KC mentioned its a standard size, WRONG. The hose end of the wet dry vac has accepted any standard vac attachment I have put on it. The new vac is a DIFFERENT SIZE!
The attachments for the wet dry vac do not fit on the new model. The attachments for the new model are too big for the hose end on the wet dry vac. I have no idea what size it is but if anyone knows Shark vacs they have a special size and its not even that.
EDIT - Now I am pissed. Took a attachment from my Kenmore house vac, fits wet/dry, does not fit new vac. Grabbed the caliper; wet/dry vac attachment ID 32mm nozzle 31mm, new vac attachment ID 33mm nozzle 32mm. BTW Shark vac attachment ID is 35mm.
The new model is for the ladies and the wet dry vac is for the guys.
IMHO dont bother with the new one and just get the wet dry vac. I would of been better off keeping the M12 and not getting the new M18 one. At least the M12 had I think the standard size nozzle...