Perhaps I'll do an addendum to Michael's review at some point as I, coincidentally, have been working with an H4D-60 over the last month and a half. But these are the Coles notes thus far:
I use an H3D-II 50 and I more or less agree with your review.
-- UI is a struggle at first for someone not familiar with the "H" ethos. But it's getting less-so fairly rapidly. That is, the UI is growing on me. There's actually a lot of fairly powerful functionality hidden in these cameras, and I suspect that the H5 has even more. It's just a question of figuring it all out. This is a camera that has had me in the manual a lot.
The camera controls are indeed reasonably well set out and do what a photographer needs. The manual is well written and explains modes which I do not use but could be useful (for example, the meter can be set up to display zone system units, etc...) and the buttons can be reconfigured. There is a memory for personal configurations.
What I don't like is the small buttons in the slot between the grip and the camera and the fact that the remote cord plugs there.
The back UI blows. But it, too, can be made pretty functional with not a huge amount of practice. One really nice feature is the instant focus confirmation, which allows any of a number of buttons to be programmed to provide a 100% zoom-to of the point of focus during initial review. This works well, despite the piddly screen resolution.
The screen of the older H3D-II is worse and the even older H3D even more so.
Apparently, the back electronics are a major difference between the H4D and H5D and are much faster. I would have liked to see this point addressed in the review.
And the files. Wow. MF finally looks the way I've always hoped MF files to look but have never quite achieved with either my Pentax 645 or D800e. The files have 'depth' to them. You can bend them into pretzles and they hold. Two spots under at ISO 200? No problem, it all comes happily back in post. Want to go hard on the sky with a Clarity brush? No problem, nothing gets crunchy. And the skin tones.......yup.
The files are impressive and Phocus is a surprisingly good application once one gets to know it. But I would not say that there is so much difference with the D800 as to sensor performance (except higher resolution). The D800 files can be heavily manipulated as well. When I tried the two cameras on the same scene, the differences in sensor appeared to be tiny and mainly due to the post-processing application used.
Where there is a clear difference is, obviously, resolution and base sensitivity.
Where there is another big difference is the lenses. Hasselblad lenses are extremely good. Nikon lenses have been, to me, rather a disappointment (personal taste rather than objective performance).