I've had mine for a couple weeks now. I haven't been trying to stress-test it, just light routine use day-to-day so far. Maybe I'll have more to say about it after I use it for bigger projects, but I guess I can share my thoughts so far.
TL;DR - I got it to replace my old Charge, and I think it's noticeably better in every way but one, which is that I like to extend one of the handles when I'm using a driver and the Arc handles don't stay in place for that.
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I like it a lot overall. The blade is great. I find the Free series blades to be easier to use than those on the Wave/Charge - something to do with the shape of it and the position in my hand when I'm using it. It's a little more blade-forward than the older design and I find it easier to control. I haven't done any serious cutting yet, just whatever came my way in terms of cardboard, packages, bits of string and plastic, some slices of food for the kids, sharpening pencils, etc. It hasn't needed sharpening but I have tuned it up on a ceramic kitchen rod and that worked well. The thumb stud makes it much easier for me to open than the other LM tools I have with cutouts. It doesn't flick out but it's very smooth.
I have seen posts here referring to other posts elsewhere about problems with the wire cutters. No problem with mine to date. I'll post if I have an issue. I've only snipped through some copper wire and guitar strings so far and it worked great for that. This is the first LM I have with the replaceable cutters; I can only compare it to my older models with integrated cutters. It feels superior to those; it cuts more easily, and the fit is tighter, which eliminates the side to side play that sometimes lets thinner pieces of wire slip between the jaws and get bent rather than cut.
Opening the awl requires care. It comes out in a clump with the flat driver and small bit holder; the edge is long and sharp enough that you really don't want to push against it to open. Seems like it would be easy to cut yourself if you weren't careful or separated the tools too early. The best way I've found to do it one-handed is to open all 3 of the tools almost all the way together, and then separate the other 2 and push them back.
It's a much better awl than the combination awl/flathead on the T4. It's put a couple of nice quick holes through leather so far, and it doubles as a "package opener" pretty well. I still like the package opener on my T4 better for that purpose (for that matter, if I'm doing anything that's heavy on opening or breaking down boxes, I'll use one of those snap-off utility knives), but this is fine.
The integrated flat driver is good; I miss the package opener on the side of the T4 large flat driver, but as a driver the Arc works better. It's a little wider and the corners are a little sharper.
No issues with bit driver retention so far, everything works fine in that regard.
My only real gripe with the tool so far (as mentioned above) is that when I'm using a driver, I often open one of the plier handles out to give myself a longer and better-centered grip, and on the Arc, there's no friction or detent of any kind to keep the other side of the handle against the plier head. It tends to want to swing open. I can't see any way of keeping it in place other than actually holding it there. I was able to use it in this position, but I had to be pretty careful about it and I could see myself getting a bit frustrated with that if I needed to do a lot with it.
The scissors and saw have to be opened underhand (if you're only using your right hand). It's a little awkward but it works. Overall, the fact that all of these tools can be opened from the outside is, in itself, a great improvement for me from the Charge/Wave platform, and the fact that I can do it all with one hand if I need to, awkwardly or not, is fantastic. No more messing up my fingernails or using a key to dig out tools.
Despite its weight, I find it easy to carry with the pocket clip. The Charge weighs the same, but it's noticeably thicker and the pocket clip is looser (Charge on the right in this pic):
The Charge was always kind of slinging around in my pocket and it slipped out sometimes when I was sitting down. The Arc isn't quite as unobtrusive as the (much lighter) T4, but in practice so far I don't notice it unless I need it, and then it's there, which is what you want. I can't speak to the sheath because I don't carry stuff on my belt anymore.
It feels good in the hand. I have larger hands so I appreciate that it's slightly longer than my other LMs. I haven't found it any more slippery than any of the other tools. The clip and other protrusions on the surface make it easy enough for me to maintain a positive grip on it. By comparison, the texture on the T4 never felt like it did anything, and the handle is pretty small for my preference; the surface of the titanium on the Charge scales looks like it has more texture but actually slips more in my hand.
Overall, so far it's been a great upgrade for me. The last time I bought a full size Leatherman was almost 15 years ago and it seems like a lot of things have been thoughtfully optimized since then to remove a variety of small annoyances and points of friction (literal and metaphorical). Solid birthday present to myself.
