Totally over-priced. An old 300mm Nikkor-P from the 1960s is just as good. At least it will be until the APO-Telyt's price drops low enough for me to buy a backup copy if it.
Seriously, what I dislike most about it is the cost to repair after I do something stoopid with it. No matter what the cost I'll get the repair done.
The purchase price of this lens made me procrastinate for many years before buying it. One thing that held me back was the gnawing fear that I'd spend a fortune on a lens that I wouldn't be able to use effectively on my wildlife subjects, so to address this fear I bought and used several older (less expensive) similar lenses: 300mm f/4.5 Nikkor ED AI, AF 300mm f/4 Nikkor ED, 280mm f/4.8 Telyt, 250mm f/4 Telyt for example. I also learned how to get a lot closer to my subjects, not that this skill would be needed for landscapes and architectural photos.
What I learned: I like good bokeh, good flare resistance, a close minimum focus distance and a good rotating tripod mount. I also learned that I dislike weak color saturation, image quality that deteriorates quickly away from the central part of the picture, and poor ergonomic design. The 280mm f/4 APO-Telyt-R is as close to Nirvana as I've found. A thoughtful soul loaned his 280mm f/2.8 APO to me when my f/4 lens went to Solms for its first repair and I was VERY glad to get my f/4 lens back! The f/2.8 APO's only advantage is f/2.8. Flare resistance, bokeh, image quality, minimum focus distance and handling are all much better with the f/4 APO.
The one thing that I think could be improved is the rotating tripod mount's resistance adjustment knob (which I believe was improved on later models). It's also big and heavy for its speed and focal length, but as far as I'm concerned the image quality and handling far outweigh my picky little complaints.
To use the lens on the SL2 you'll need to get it converted to 3-cam, so don't pay any extra for a ROM version. The view through the SL2's viewfinder with this lens attached is simply stunning.