Hi Martin! I got my RF645 & lenses about a year and a half ago, to replace a Fuji GS645S that I'd bought used and which turned out to have several serious problems, said to be infeasible to repair. The Bronica is a more solidly-made camera, and more sophisticated.
The 135mm lens situation doesn't bother me either, except that I'd like to have one. It's very much like the Konica Hexar RF lens incompatibility issue, involving manufacturing tolerances "stacking" up to cause some folks problems and evening out for others. And a public relations nightmare for the maker.
Dealer Robert White in the UK offered a matching service to tune the 135mm lens to a customer's camera body. And after Bronica recalled the lenses and refit customer bodies with 100mm framelines, Robert White bought up many 135mm lenses and continued to match them.
While I'd like to have one of these matched sets of body+135mm, I haven't actively chased one down... since like you, for me the 45 & 65mm get the usage.
The camera feels good in the hand, with a thumb recess on the back and finger grip on the front, and controls in good places. Except the exposure compensation dial which doesn't lock and can get moved inadvertently. It's as easy to load as a 120 camera can be, I think, with nice pop-down spool retainers, auto positioning of the first frame, etc. Pretty similar to the Fujis in this, and in the ease of switching from 120-220 and back. Certainly a lot easier than the Pentax 67 which has twist-latch spool retainers, and separate switching of the frame counter for 220.
Switching lenses is made easier by the automatic "dark slide" curtain that is drawn across the film as the lens is twisted off the bayonet, and retracted again as the lens is clicked into place. The Mamiya 6 and 7 cameras have a separate manual control for this.
Some have criticized the Bronica for having considerable delay in the shutter release, as there's an odd soft wheeze-click that comes a bit after you press the shutter. But this is not the shutter tripping; instead it's the camera electrically recocking the shutter automatically after release.
With larger film formats, the lens quality gets less critical, except at very large print sizes. I haven't made prints larger than 8x10, but so far I'm pleased with the "look" of the Bronica lenses. No visible barrel or pincushion distortion, smooth out of focus areas, and a general richness that I think comes from the larger film.
As far as I can tell, mechanical and optical quality of body and lenses is first-rate.
Others have brought up the film orientation issue, some violently against the vertical framing. Of course this is the same as in a 35mm half-frame camera, and when those were fairly popular I don't recall hearing much fuss over it. Indeed, 6x4.5 is a half-frame format too, compared to 6x9.
One way to avoid turning the camera is to choose a square format like 6x6, and many shooters quote this as their major reason for liking 6x6. I never have cared much for square formats, figuring it's just procrastination for cropping to rectangular (v or h) later! When I have shot square, I've composed square, so usually end up with square prints.
So I think the vertical orientation thing is overblown. Just as unreasonable to complain that horizontal orientation cameras require one to turn 90 degrees for vertical shots. Now, if you do anticipate mostly horizontal shots, then I think it becomes a valid preference. It comes out about 50/50 for me, so I don't care.
As to 120 film, or any other film, the sky is falling, isn' it? I mostly use 220 and find plenty of choice... except that chromogenic B&W films only come in 120. A lot of film formats died long before digital came along, but 35mm and 120/220 and 4x5 are such popular standards that will probably be available for decades to come.
It would sure take a dedicated hobbyist now to use a camera taking 828, 616, 122 and such. And it's getting hard for folks with 127 and 620 cameras. These and 16mm can be rerolled from other formats or slit to fit. I bet it's going to get especially hard for film in proprietary plastic cartridges like 126 and 110... APS is out, but I think 120 and 35 will go the distance.
I very much like the Bronica RF645; it's an excellent product. But this may be the last major film camera system introduction. I don't see Bronica doing much further development on it. I'd love a 30mm lens, but they're still offering rebates to get the cameras out the door, so a new wide-angle lens sounds unlikely.
Anyway, I'm tempted to get a second body and just enjoy. BTW, I found a Fuji repair expert who fixed GS645S damage, so it's working like new (this is the all-manual camera with fixed 60mm lens). And, curious about auto-focus, I got a used Fuji GA645Wi (fixed 45mm) too. As you might see from my pics in this forum, I'm mostly doing environmental portraits often in dim interiors with Fuji NPZ800 film. I'm pretty happy with how it's all working out.
Hope all this blather will be of some use.
Doug