my take: how it feels in the hand.
That is fine. I am in the same camp. However, after holding so many phones in my hand (dummy and real ones), I have a rough idea on dimensions. For example, I would prefer 60-65mm width and I couldn't care less about length and thickness (no idea why they keep thinning it, if they stay with 8-10mm thickness the battery situation would not have been this bad). However, I have also found that the curve-ness or how tapered the edges are may allow me to accept one that may be >65mm. So what is yours? If you have not nailed down the numbers, you can tell us which previous phones and recent models that you have tried feel good in your hands? From there we can extrapolate.
On closer examination of the specs, looks good.
I would say beware of Sony phones. They have a tendency to disappoint and you do need to know what you are getting yourself into. Since the Z1 mini (official name still be be unveiled) is still in the rumoured stage, we won't know for sure the final specs. My previous phone is the Xperia Arc so I can say a thing or two about them. I believe they have improved a lot on the OS update side so you don't have to worry about that. However, the screen is still an issue with complaints of the yellow hue and not "true" IPS (i.e. still viewing angle issues). And yes, even on the flagships Z1 and Z Ultra. Plus, Sony has stated on record that they are not going to focus on the US market for the near future. This means you either have to pay full prices for importing or buying direct from Sony or its affiliates (Amazon and Newegg are included, so it is not that bad). There is also the fear that they won't even have North American variants available (especially ones with compatible LTE bands) or the NA variant will be released much later compared to the rest of the world. And the last thing: they are almost always overpriced coming out of the gate. You can't beat a Nexus and the Moto devices price wise.
For me, I got tired of waiting for the Z1 mini and reluctantly switched to the Samsung camp for the S4 mini. Granted I paid full price for an import so I had it before the US carriers released it.
How do you like the S4 mini?
It is the first "mini" version of phone other than the 2011 Xperia Ray where the specs are not that crippled. The S3 mini was stripped down too much from the S3 and IMO is crap. The S4 mini features a non-pentile AMOLED screen which is nice. The size is small compared to my Arc (mainly the slightly smaller width and the tapered back). The dual core and 1.5gigs of RAM are actually good enough for the qHD screen, with the added benefit of lower power consumption. The GPU is the Adreno 305 so it is not last year's model as well. I really do wish it were 720p (which would be the Z1 mini, SP, and the ZR that I was looking at during my decision time), but the S4 mini did not seem to have the nagging issues of the SP/ZR. I just convinced myself to switch camps.
I haven't added all my accounts for syncing yet (the worst offender battery wise is Exchange), so battery use has been great so far.
I imagine I will have to go back to larger daily charging cycles once I have synced everything and installed all my apps. I just did not have time to load all the stuff up yet (and to read up on how to root the thing, I heard that Xposed is super powerful).
Edit: I can comment on the stock software later, but for now I should bring this up as well: the S4 mini does have a removable battery, if that is your thing.
The Model M is not for the faint of heart. You either like them or hate them.
Gerbils unite! Fold for UnitedGerbilNation, team 2630.