Hi Gary
I've owned this lens for probably a decade now. When it was first released it was widely criticised on the forums as being too slow (f8), not rangefinder coupled (guess the distance), with too long a minimum focus distance (23 feet) and too short a focal length when compared to the 150mm, the argument being one could just crop images from the 150mm.
On the other hand the lens is light and incredibly sharp. For distant landscapes, set to infinity or near that, the lens is great. For objects say 50 to 80 feet away, I normally stop down just in case. I have stood there wondering how far something is away getting very frustrated and I have also stood in five feet of water on the north coast of Bali taking silhouettes of fishing boats against the sunset loving every minute of it and the 6 feet wide prints afterwards. I would prefer if it was 250mm (or longer) and coupled, but it isn't. My advice, for what its worth, would be that if you see yourself shooting lots of landscapes, focused on infinity at f11-ish, then get it. Otherwise, crop from the 150mm.
The viewfinder is bright, has lines, as Oren Grad says, for both 150mm and 210mm and I think useful for the lens.
Simon
