The R-E is a cut down version of the R5. It has aperture priority plus manual exposure, and has shutter speeds upto 1/2000 sec. Spot metering is available in both modes, plus average metering is available in aperture priority mode. The camera is relatively small in size.
The 50mm summicron-r is built beautifully. The focusing is silky smooth. I have yet to develop the first film I shot with it, so can't comment on image quality yet. But holding the lens is a pleasure and you can see straight away that these lenses are built to a very high level of standard.
My first impressions are that the Leica R-E is quite well built - though not as good as the Nikon F2 or F3, both of which feel sturdier. The Summicron-R is, however, definitely better built that the 50mm Nikkors.
Here are some pictures of my Leica: