First impressions: Saucony Triumph ISO 4

I just got the new Saucony Triumph ISO 4 in order to test out what Saucony has come up with. This shoe is the first of the flagship five from Saucony (Kinvara, Ride, Guide, Triumph, and Hurricane) who have implemented the Everun into the entire midsole of the shoe. Both Freedom and the newly released Lincoln do this, but among the top sellers (at least in Denmark) there has not been such a huge new development in years. 
The amount of Everun in the midsole will impact the shoe both in positive and negative ways, it's a heavy compound, more unstable, but offers vast energy return improvements over traditional EVAs.
These are my first impressions after 29 kilometers of using this shoe.

The fit

The ISO fit does as usual feel very light on the foot, but compared to the Hurricane ISO3 the fit is a little bit more snug around my foot. This is especially true around the toes at the front arch of the Saucony logo, where I actually felt it a little bit too tight after some hours at work (not related to running short runs).
This tighter fit makes the shoe fit better around my heel compared to the Hurricane, resulting in a comfortable ride overall on all the different runs I have tested it on so far.
Compared to some other brands this shoe is overly padded in the heel, making the fit very comfortable, but also very soft and less secure. I could imagine some people still having problems with the heel slipping sometimes, but have not experienced this myself.  

The stability

The initial test at work showed that the shoe holds my ankle despite my tendency towards mild overpronation. This was concluded after slow-motion videos footage at work. But curiously we also noticed that the ISOfit upper has close to no stability features around the arch and heel compared to other neutral shoes that I have tested. This has resulted in very tired muscles around the ankle and calf after both running and walking.

The feel

Running in this shoe is like running on a cloud. I run with both firm and soft shoes, and this is probably one of the softest soles I have ever tried. Every landing impact is reduced greatly, making the run very comfortable. The Everun technology hides behind very impressive energy return numbers, but I must admit that the shoe still feels very unresponsive, and I cannot stop thinking that the recent talk of energy return to being a marketing ploy more than an actual useful parameter for judging a shoe. Fast runs are thus not the best fit for this shoe. It seems better at slower Zone 2 runs where responsiveness is less likely to be a factor.

As an extra test, I used the shoe at work for an entire day and noticed that I got exceedingly tired in my calf, foot arch, heel and underneath the toes because of the extreme softness. I will not be wearing it at work again.

Overall

After these initial first runs, I will be focusing more on using the Triumph for slower and longer runs, as this is clearly where it is most capable. Both the narrow toe box and the arch support are issues I will follow up on and consider moving forward.
The Triumph ISO4 has both impressed me and let me down at some aspects. I will continue to use it for the months to come in order to get a better and more complete picture of what the shoe is capable of.