FYI, this is my first review...
A little background first: After upgrading to the 5D4, I was left with the 5d3 and 5d4. Since I'm not shooting as many weddings as I thought and mostly reaching for the newer toy, the 5D3 was gathering dust and I've been itching to add a crop sensor camera to my kit. The M5 caught my attention.
Overall image quality: I give it 7/10 when used with EF-M 15-45 kit lens and bump that up to 10 when used with my EF lenses and the adapter ! This little camera rocks and I will be getting the EF-M 22mm f2 which is highly rated. This camera also sports the same image sensor as the 80D which is great. (most of you surly know this already)
Value for money: Solid 9/10 for me. No, it's not the best mirrorless out there and certainly not the cheapest. The clincher for me was the Canon adapter which enables me to use all my other lenses without any compromise on focus accuracy or speed. I'm not a 3rd party adapter kind of guy...
Must Have: Score for me is 9/10. Simply put, this camera works very well and is a great compliment to my FF camera. Very nice option when you want to take photos that don't have to be taken with a FF camera to get great results.
Suitability for intended use: 10/10 since it does what it sets out to do. Provide excellent image quality in a compact package. Great for the times you want to travel light.
AF Performance: 7/10 simply because it's not as pin point accurate compared to the 5D4. Face detection is good but could be better especially compared to Sony's eye detection.
Handling and Ergonomics: For handling, I give this camera a 10 since I'm very familiar to Canon's menu system and how the camera works in general. For ergonomics, I give it 7/10. Reason for this is that coming from DSLR's I definitely needed a couple of days to get used to the small form factor. I'm OK with it now but it's still not ideal for people with larger hands !
That said, the slight ergonomic inconvenience is countered by it's portability. I find myself bringing the M5 and taking more pictures than ever before because of this. I love my DSLR but it sometimes stayed back due to it's size.
User-interface: Gets a solid 9/10. The touch screen as amazing and all the dials and buttons are positioned logically. I didn't bother setting up back button focus since I love the touch/drag focus using my thumb, then half press the shutter to focus and finally take the photo. Moving my thumb over to back button focus would waste time.
Conclusion: This camera is awesome and I don't care what anyone says. Is Canon late to the mirrorless game ? Yes but that takes nothing away from this camera. Are there better mirrorless systems out there ? Yes but if like me, you're heavily invested in Canon Glass and you're looking for a small mirrorless camera to compliment your bigger FF Canon camera, the M5 is the ticket. (for me anyways)
My EF lenses behave exactly the same as if they were mounted on my 5d4, which was crucial for me. Could I have purchased an A6500/Metabones adaptor ? Of course but I'm not a fan of using gear from 3 different manufacturers at the same time...too many things can go wrong.
Hope this helps !