I was looking around online at Canon's refurbished lens store last week and saw they had an additional 10% off on some lenses, bringing this lens way down in price. I figured I could easily get my money back out of it or, worst case scenario, return it. But that ain't happening. Didn't see anything written up about this one so here you go...
Extending the Lens: For those that don't know, this lens is very compact, but has to be "extended" for us (much like a lot of mirrorless kit lenses do) so you flip a little switch while turning and it locks into place ready to shoot anything from 1:1 macro to infinity. Then, if you activate the switch again, you can turn it a little further to get to a "Super Macro" mode which is like 1.2x macro. I saw on Dustin Abbott's review that his lens didn't "click" into place when you engaged it. I don't know if he got a faulty lens or if it's something Canon has changed in later releases, but my lens clicks into place at the normal shooting stop and the release button has to be very deliberately engaged in order to get it to collapse or go to Super Macro.
Build Quality: It's fine. The lens is incredibly small and light, but feels fairly dense for such a small and light lens. The f/3.5 maximum aperture probably has a lot to do with this as there's not a ton of glass in there. It has a plastic mount, which doesn't bother me. I know some people get all worked up about the lack of a metal mount, but I don't mind it on a lens this small and light as it's unlikely that it'll ever break off. And I can't see myself mounting/unmounting this enough times for it to wear down the plastic flanges and cause an issue. Lord knows I don't keep gear long enough to do that!
Lens Hood: This is stupid. The built-in macro LED lights are a neat feature, but they designed it in such a way that filters can't be used normally and a lens hood can't be attached via the standard bayonet mount around the front of the lens. I think they could have done better here, but the (thankfully) included metal lens hood/filter adapter screws on, blocking the lights. This should have not covered the lights. The screw on part doesn't bother me, but I think it could have been a more traditional lens hood design that stuck out in a petal shape or something along the lines of the Fuji X100 hood shape. Effective while not interfering with the LED Lights. If it had been designed differently, the front of it could have been threaded to take a more standard 49mm filter thread or the like. As it is now, it takes 43mm filters. Dumb.
Maximum Aperture: I realize this lens won't be useful at very close distances at f/3.5, let alone something faster, but for general shooting, I'd have liked at least an f/2.8 or an f/2, even at the expense of a little size and weight. The current maximum aperture, while useful for keeping the size and weight down and giving a smidge more DOF during super close focusing, feels a little weak to me and Canon should have given us at least f/2.8.
LED Lights: They're fine... They don't put out a whole lot of light so won't be good for anything but macro work. And they're a little harsh and "artificial" feeling. I'd probably rather use the little adapter hood thing and use a regular old ring light or an off-camera flash with triggers and a soft box to light my subject than to use these little lights. Although, for shooting very small objects like jewelry or whatever when you don't have much of a light setup, they could be useful, I suppose. I just wish they were brighter and a slightly larger source to soften them up a tad.
Focusing: This thing is snappy and fast. Video focusing all the way down to macro distances is smoooooooth and quiet and amazing. Which is good, because I plan to use this as a video lens with my M5. Manual focusing sucks as with most STM lenses, but it's better on the M5 with peaking than with, say, an EF-S lens on a canon DSLR or the like since the peaking shows you real time changes in focusing where you can't really feel it.
Video: Works like a champ in video (as stated above) and I plan to use it almost exclusively in this way. I do reviews of pens and what not on my blog and I plan to use this as a sort of "tabletop" review lens where I can position the camera between myself and my subject and cover the item along with all of the details easily and effectively. A lot of people sneezed at the 28mm focal length, but for this kind of stuff, it's PERFECT. I'm happy.
Overall First Impressions: I'm surprisingly happy with this lens. I see why some don't like the focal length. It's a little non-traditional for macro work. But for my intended use, it's quite nice. I don't like the lens hood/adapter situation. Canon could have done better here. This solution feels lazy. Having to extend the lens for use is a bit of a pain, but it's not a deal-breaker as most people will likely leave it extended unless they're putting it back in their bag for the day. Even then, I guess you could leave it extended. Focusing is quick and snappy and smooth.
Canon's EF-M lens lineup has left a lot of people wanting. Their variable aperture zooms aren't totally inspiring on paper, although most, if not all, of them perform better than most would expect. Would a 35mm or 55mm f/2.8 have been a more welcome focal length for this system? Probably. Especially given the very good little 22mm f/2. But I think this shows Canon is at least doing something with the EF-M lineup. Even if it is kinda weird.
I don't think this lens replaces the 22mm f/2, which was what I was sort of hoping for, but it's small and light enough that I don't mind carrying both.
Hope this was helpful!