There are over 85 reviews from actual Amazon.com customers who bought the Milwaukee 6390-21 circular saw. As of this writing here is the break down of how they rated this saw:

Here are some snippets of what owners are  saying about the Milwaukee 6390-21:

Great saw – by Steve Vankast

I owned an older model of this saw and it was stolen. I read all the negative reviews, ordered this saw and I love it…..The depth adjustment has been improved and now works fine over the old model…..I think this saw will last a good long time and I was amazed at it’s power…..

Awesome saw – by Alex Turner

I purchased this saw based on other reviews here at amazon, and I have to say I was not disappointed. It’s base is a perfect 5″ offset, which makes measuring cuts fast and easy…..The hex wrench for the blade arbor is stored on the saw itself which means you don’t loose it. Just for a bonus this comes with it’s own box which stores the saw nicely….. would definitely recommend and buy again.

Not bad but I haven’t found a saw that I can rave about yet – by C Hepburn

Pros:
The base was square to the blade out of the box. I returned a saw without even plugging it it because the base was out by 3/16″. This one, however, was very close which makes for square speed-square cuts.
Lots of power. I ripped a 12′ 2×10 without the saw lugging.
You can easily see the cut line from both sides of the blade…Cons:
I guess you could count this all as one shortcoming.
Where’s the rip guide? I see the spot for it in the box but it is not included for some reason.
Alright, I sucked it up and bought the Milwaukee rip guide for an extra $11.

What a difference a quality tool makes! – by tano

This saw was actually one of the first quality power tool purchases I had made a few years back…..I went to my local Sears that happened to stock all three saws and compared them. First thing was that the Milwaukee came with a case which I was looking for , and once you put the three saws side by side, the Milwaukee just had great features…..I thought the adjustable handle was going to go unused, until the first time I made an adjustment and realized you can really tailor your hand position to the cut…..But the thing that has impressed me most is the power of this saw….I have built two decks, several hundred feet of fence plus a major home renovation and would absolutely buy another Milwaukee if the need arose.

Professional quality – by Carlton D. Walling

I’ve been using a craftsman for 35 years. I finally broke down and bought this Milwaukee. It flies through treated boards like a knife through hot butter. Wouldn’t hesitate buying this product again.

Consumer Reports was right – by KaneoHed “Stuff Guy”

Tilt-Lok is the best innovation ever, enabling the user to choose the best “angle of attack” to comfortably and safety operate this saw. Very smooth operation. Not heavy. #1 rated circular saw by Consumer Reports.

Buy this saw – by Namshub

Another excellent tool from Milwaukee. The adjustable handle is a very nice touch. It is not too heavy, but is still very rugged. The base was dead flat. Switching blades is a snap…..The best thing about it is that it just works like it is supposed to day in, and day out.