It is probably like with every technology driven system. The experience and performance gap of the newest version vs. the previous generation immediately preceeding it is most likely the smallest gap. With each predecessor generation, the gap widens to the newest entrant - increasing the benefit and likelyhood that someone might think about an upgrade.
It is similar to the sharpness discussion with lenses which often dominates in internet discussions all the other attributes of lenses. That cameras are often reduced to their "faring" wrt to their high ISO performance. They are a complex system and my approach has been to rather appreciate the "holistic view" (if there can ever be a holistic view
). Hope you get my point, it is the combination of technical performance, plus all the other factors like usage, handling, familiarity, sturdiness and reliability. Seen from this perspective, the first 2 days (rather one long day) with the D5 leaves the impression that it is a very well rounded package. Streteching the envelope a bit here, a bit there, but ultimately, that the "reliance factor" on this tools is again moving up the scale. Even vs. the D4 I used for a few years now (I don't have a D4s). Things like WB accuracy in difficult lighting conditions, combined with the better AF performance, which finds not always a contrast line to hook on, but seemingly more often than the D4 or D800E, or the exposure meter, which more often nails it better than the cameras before. There is no single magic itemand I can't claim that the D5 does all right, every single time and never fails. Of course it sometimes "fails", it sometimes needs support with settings as it can't have insight into my intent, but the overall experience is that it is a significant step forward in this broader perspective.
After this first experience, I would describe it in the following way (for me). Despite (or rather because of) my familiarity with other Nikoen cameras, someone feels immediately "at home". No surprises. No rough edges someone has to keep in mind to avoid unexpected behavior. If I would need to prepare for a shooting in "the unknown", the D5 is a formidable contender to be picked. Being a long time D800E fan for this pick, the D5 will probably replace this default choice in my personal selection. Leaving the additional feeling that the D5 is ready for photographic exercises I personally have no experience in yet (i.e. sports photography). In this regard, it leaves the impression, that it will support your next photographic endaveour - whatever you choose to embark on. Please don't take this as an absolute statement, that only the D5 can do that. By no means, other cameras are great as well, but the D5 provides this feedback, that this journey will be this tad simpler with the D5.
On a side note:
Based on this extensive day of shooting with the D5 and the AFS 24-70mm/2.8 VR, I have to reconsider my previous assertation about this lens. Originally, the difference to the predecessor was seen too small to justify the investment for a purchase. While the long term "fault" of the older version was that it didn't emotionalize with single attributes like a Noct, it rather delivered in a very non spectacular way. It just delivers and delivers. Day in day out. The new version might be plagued by the same "problem" when I first used the lens for a quick test. After this day, I need to confess, that the lens worked with every single image towards this "goal" - "Trust me, I will perform and won't let you down". While i like the AFS 300mm/4 PF very much, it came up yesterday with another unexpected behaviour, probably caused by the Fresnel lens design (I'll cover this separately). The 24-70mm VR didn't have any of these surprises.
While I started with the normal approach a camera is potential design for - by shooting what I like - I didn't do any formal test. I assume they will come in in droves in the next weeks and months.
Happy to share my personal approach to get a feeling about the ISO performance envelope of a camera. It starts with filesizes of dark frames. Quick and very easy to do. Camera, no lens, but lenscap, set all things like NR=off, Save to NEF/14bit/lossless, Manual expose, with 1/125s and create one dark frame per ISO Setting (I do full EV steps). Noise are artefacts in an image, which is bad. The good thing is that the overall level of noise need to be stored somewhere. The lossless RAW format is a good proxy for the increase in level of noise a camera HW&SW produces. Just watch the file sizes grow and put the base ISO at 0%.
The second part is viewing the dark frames on my screen - skip through the different ISO levels and get a feeling when the distracting noise becomes so visible, that I want to be careful starting with this setting. Nothing scientfic, just a very quick overview to know where to spent more time in assessing the boundary conditions to better know your equipment.
1) Filesizes and rate of growth for a few cameras
2) D5 Screen capture of NX-D overview
3) D4
4) D800E
