Currently a Glock 19 owner but I held a PPQ M2 today at the local fun store and WOW. The trigger was excellent dry firing and it fits really well in my hands.

For those of you who own the PPQ M2 in 9mm what are some of the good and bad things you've experienced so far with use? And is it worth it to get the Navy model over the regular PPQ M2?

If you get the navy it comes with a threaded barrel and the 17 round mag.
If you plan on shooting suppressed, make sure it is one of the newer ones with the updated springs, search the Internet for specifics.(navy model)

You can't beat the PPQ.

It's one firearm that will never require a aftermarket trigger, to make it great. The only con just like many firearms, is stock sights lol... shoot accurate out the box and runs any ammunition.

Swapping sights on that one is ridiculously easy

What is required for a sight swap?

Allan wrench and a screw driver. No pusher or specials tools required. The rear sight pops right off

You can simply depress the plunger on the rear sight adjuster and slide it out by hand.

You will want the Glock tool for the front sight.  A very thin walled socket will work, but Glock tools are cheap enough.

Awesome. Thanks for the clarification.

I just did this last night. I swapped them out for some trijicon night sights. I would say it took me less than 10 minutes.

I put off getting a PPQ for a while.  Got a second P228, an SP2022 and the VP9 before coming across a deal on a PPQ I couldn't pass on.  After shooting it the first time, I was kinda kicking myself for not getting one earlier.

I have had some issues with mine, but I have not attributed them to the pistol itself.  First, I had the slide seize up just out of battery on a live round.  And I mean seized up.  No power stroking, not even putting my body weight on it with the nose of the slide against the bench.  Had to work on it at home with a covered punch and mallet.  I don't blame the pistol, as they were reloads from a previously trustworthy source.  They were a bit hourglass shaped.  They all worked fine in my SIGs, but apparently the PPQ has a stepped chamber that said no-go.

The second issue was two stovepipes and a near squib, all consecutive.  That turned out to be a bad lot of factory ammo, which the manufacturer replaced.

Most recently, I took the PPQ out on a chilly, windy day.  Was going to do a sight swap and wanted to get before and after groups to see if elevation changed much (windage is obviously easily adjustable on the PPQ).  Well, I went to shoot my first string of 15 and immediately got "click" on the trigger pull.  Chamber check, yup it's loaded.  That should've been enough to recock so let's try again.  Click.  Drop the mag, eject the round, inspect the case.  Light primer strike.  5 rounds in a row before I went back to the bench.  Took those 5 and they went off no problem in the VP9.  Tore the PPQ down and pulled the striker.  Grease.  Why is there grease on my striker/in the striker channel??  Wiped it down and reassembled and started getting ignition.  Did a good cleaning that night and the pencil test damn near put a hole in my ceiling.  I did buy the pistol used (the guy literally had it 4 days) and he had used froglube on it.  Based on that decision, I wouldn't be surprised if he was challenged enough to think lubing the striker was a good idea, but it wasn't froglube in there (at least it didn't smell like mint).  As specific as Walther is about where to lube and how much, I doubt it was factory lube.  I also seriously doubt the dabs of grease I put on the rails migrated into the striker channel.  

Anyway, even though I don't attribute any of the failures to the pistol, they all were serious failures that rendered the pistol inoperable.  It will be a good number of rounds fired through it before it gets carried again.

As for my set-up, I have big hands so I run the large backstrap.  Also gave the Talon rubberized grips a try and I like them.  Wish they actually added more girth to the grip.  And I did manage to get the sights swapped to Mepro 18801s.  It shifted POI slightly higher, but nothing I take issue with.

Own both 9mm variations and some thoughts:
if you ever want to use a can, go Navy.
If you ever plan on using it near water, go Navy. Navy slide has a drain hole.
If none are true, either will do. If still unsure and can pay a little more, recommend Navy, preserves options and Navy enhancements are not obtrusive.
(Walther now has a threaded Barrel for the non-Navy PPQ.)

Some complaints with suppressors on PPQ on the web. Walther has a kit to fix.
I've shot over 300 rounds thru a five different cans and only had 2 failure to return to battery. (I do not have the spring kit) Saw exact same thing with the Glock. I think issue is me. I have at least a case now thru both unsuppressed, no issues.

Other thoughts:
PPQ trigger is the smoothest OOB of any striker fired pistol I've handled. Genius.
My Glock 19 trigger reset is about .25"; PPQ, probably half that. I find I put bullets inside the hole made by the previous round. For the first time I can crank the target to the end of the range and put most of my rounds on paper. Credit incredibly even trigger pull, short reset and the ergo's. It’s a natural pointer.

PPQ is approximately the same size as the Glock 19.
Bought Awesome Dawson Precision night sights. Dawson provides all the install tools. The front sight removes identically to the Glock. As mentioned by others, rear sights are pretty easy.
Other than night sights, I've really had no desire to tack on anything else to the pistol. It's near perfect for me. (so I bought two )
IMO all the drama about not having all sorts of aftermarket parts is non-issue to me.

Finally, I found I shoot the Glock high due to my natural grip while PPQ sight alignment is perfect. You may be exact opposite. IMO your accuracy with a given weapon should be the determining factor, not anything I or others say.

I love mine. It shoots straight eats whatever I feed it and works great with my suppressor.