Towards the end of last year I purchased the Mamiya 645 from a friend, I had never held a medium format camera let alone one of these beasts, however once I got my hands on it all I wanted to do was test it out.
I have the hip viewfinder version which visually is brilliant, I have found it to not be that useful as the viewfinder from my height is a little small to make sure that focus is on point.
luckily it has a magnifier on the viewfinder so you can hold it up to the eye for a perfect view.
I have now used the camera along with my digital on 4 shoots, 3 with colour film and one black and white (still waiting for that film to come back) and honestly I cannot believe the results.
The camera has no light meter so is completely manual in setting the exposure etc. As well as focusing.
My opinion is that I love this camera and it excites me when I use it as you just aren't 100% sure of the results you are going to get. Just like using any analogue camera.
I have attached some some results from the Mamiya 645.
Above is totally unedited and the model is the wonderful Maiyah.