Ok. I don't want to start another fenix/nitecore is better thread, so I'll tell some good things too.
I love the knurled body of the EX10. It feels much better in my hand than my Fenix P2D q5. The Fenix is a bit slippery to me. This was my main reason for wanting to try the EX10, easier to grip, and any excuse to buy a new light is good enough.
My Ex10 is the golden dragon model. My beam is whiter, smoother and brighter than the fenix. Its fantastic.
The low setting goes much lower than the fenix. This can be useful in many situations.
My dislikes center around the user interface. The first thing is the doubleclick and doubleclick and hold time is pretty quick. I'd guess it has to be done in under 1 second. I can't reliably jump to high and low levels yet. I'll say right up front, I have no coordination or rhythm when it comes to stuff like that. I'd need about 2 seconds or more. When I try for speed i end up with 3 clicks. I'm sure my 12 year old could do much better. This in itself is not a deal breaker. I don't particularly want to go instantly low or high. That leaves me with ramping. Holding and ramping takes about 4 seconds from low to high. But, if the light is left at some unknown brightness, I can't be sure if holding the button down is going to ramp up or ramp down. It will reverse from the last thing you did. On top of that, at certain times when the light is left at either extreme, it will not do anything when you hold, you need to click one more time and then it will ramp. You can observe this on 4sevens YouTube video if you watch carefully. If I am hiking or going for a walk or doing some extended chore, these things are not big deals. The very low is great for preserving night vision.
My problem is the way I use my edc. I whip my P2D out countless times a day, looking for parts or tools in my garage or storage area. I'm using the light for maybe just a few seconds at a time. If my 'on time' is only a few seconds, spending 2 seconds with the button is too much. For this daily use I prefer the Fenix. I pull it out, click once and the bright low is usually perfect. I need more, I bump it up once or twice more. Next use, I know exactly what is coming. My parts bins and shelves are not in the dark, I just need some extra light without turning on the room lights all day long, so the relatively bright 'low' of the fenix is great for me. I hope I have helped and I have been fair and have not bashed the EX10/D10. FYI, the 2 stage Surefire E1L works great for me too as EDC, but a little clunky on my belt. Its better for winter with gloved hands than the Fenix.