The first pair I received were somehow 2 different sizes (even though the tag said they were the same size) so I reordered them again and the next pair has been treating me well. These shoes are stick and precise, great for advanced climbers.

I bought this shoe to get a narrower fit. The shoe fits about the same as my previous men's muira model, The heel seems to have some additional material that tightens the heal somewhat. It appears that the soe is made on the same equipment by size.

I saw many people below saying they go with a bigger size in the miura than in the mythos. I think that they are not sizing this shoe properly.
The mythos is designed for your toes to be flat, much like a normal shoe, whereas the miura is designed for your toes to be curled / scrunched (which is what makes it stronger at edging). Accordingly, you're going to want to go much smaller in the miura than the size you would wear in the mythos. Otherwise there's really no point in getting the miura -- your feet won't fill up the shoe properly, it won't function as designed.
For my feet, and for my climbing purposes (sport, gym), a 39 in the mythos and a 37.5 in the miura seems to be appropriate. I found that as I tried progressively smaller sizes, it didn't really get any less comfortable, though each time I could feel my foot filling the shoe more fully. For me, in the store, the 37.5 was very difficult to put on, and was a bit painful when I walked in it. My foot also cramped up a bit. But, after a few weeks of climbing 3 days a week, it has stretched a bit and I think it is absolutely the right size. Now it is comfortable enough for a few pitches. I believe in the future it will become still more comfortable. I On the basis of that, if you're looking to use this for sport or gym, I recommend shooting for a sizing experience similar to the one I describe (if, that is, you're sizing the miura). Of course, your mileage may vary.
But remember, if you don't want to scrunch your toes up, you should probably just get a different shoe, or stick with the mythos.
Hope that may help you shoe buyers/sizers in some way.

I love these shoes. I had the 5.10 Coyotes but needed an upgrade in the toe. With the Miuras, I can finally stick those tiny footholds with full confidence! They fit my feet perfectly and the lining is soft. I wear a 7-7.5 street shoe and got these in a 37. My feet are slightly wide in the forefoot and narrow in the heel. They are stiff and uncomfortable out of the box but after breaking them in in 2 climbing sessions, they are now perfect. They did stretch a bit, less than half a size. I thought the laces would be annoying but nope! I'd definitely buy these again.

I wear a size 6 womens, bought a size 4. I have been wearing them for about 3 weeks now and they have stretched to become the perfect bouldering/sport climbing shoe.

I love these shoes!!!!! They DO stretch, but not as much as others told me, so get them small, but not too small. They have unparalleled fit, and I love how well they toe in. I doubt I will be able to wear other shoes after these.

I´ve been using my Miuras for a month. No disapointments at all. They are just great. It sticks in some imaginary holds that I wouldn´t think. It hurts a little bit in the first uses, but worth the pain. Now they are much softer, and already raised my climbing level.

I usually wear a Ladies 6.5 in street shoes, and I had to get a 35 in these. The fit my foot really well.

Had them for about a year and they are still holding up pretty well! I wear a size 8:5-9 shoe and got these in 6. I was in pain for about a month. But, after the break-in, I can't rave enough about them. They are wonderful and last a long time. My girlfriend also wears the same exact shoe - she is on her 2nd pair!! Gym or real rock; these shoes rock :)

I wear a 35.5 in sportiva mythos~ 35.5 in the miura was waaaay too small

This shoe improved my climbing as soon as I put it on. Great edging, and the rubber is a lot stickier than the other shoes I've tried. A little uncomfortable at first, but they broke in nicely (still a little tight during cold winter bouldering in WV). The only problem is that the sizing is kind of off. Definitely go down at least a size and a half. I wear a 37 in street shoes, but my Miura's are a 35.5.

For my new Miura's :) Out of the box, they edged, smeared, and basically upped my grade instantly. I powered through imaginary footholds and the Miuras held every one. Be sure to go about 1.5 sizes down from your Euro street size when ordering. Haven't tried them on cracks yet, but, pretty sure they'll go anywhere I want to go, and with style bonus points. Not comfy enough to go for a walk in the park, and might need to be broken in a bit before going on a long trad climb, but if you want to go kick butt on a sport route right away, give 'er.

I tried on both the mens and womens and the womens fit a lot better if you have a narrow foot. These shoes instantly increased my climbing capabilities in the gym. I have yet to take them outside, but I am sure they will do fine. The shoe seems to stick to the smallest worst foot hold with ease. A little pricey but well worth it

These shoes kick ass. They are a true women's performance shoe, narrow in the heel with lock-down lacing. If you don't get them too small, they can actually be comfortable for more than one pitch, too!

I wear my Mythos in sizes 38.5 and 39, but I've found these are best in a 39.5 for me. I wear a size 10 street shoe.

bought these for my husband and he cannot stop raving about how great they are. they are great for crack climbing and edge really nicely.