I am starting with this lens because, for most people, this is one of the first lenses they will try to adapt. It is also super popular, and you are about to understand why. This lens was first made in 1971, marking a notable release by Canon. Some of its new features were game-changers. First of all, at that time, the optical quality and sharpness were off the charts, and it still is today. This kind of image quality just was not something people had seen before, it was brand new. Fifty years later, there is a reason this lenses value is still increasing.
What is special about this lens?
Obviously, if you are getting this lens, you are already hoping to get an older film look out of your photos. For this reason, the first thing I am paying attention to is what is unique about it. My favorite thing about this lens is the Bokeh. Bokeh is the part of the photo that is unfocused or blurred out. The 50mm makes a beautiful, slightly messy bokeh in its background. The slightly imperfect blur is so unique, especially if you shoot on a low aperture setting. The aperture goes all the way down to 1.4, which is super low, and you can really see the unique bokeh effect when shooting on this setting.
Next, I have to mention the price because I think I bought this lens for about $60. I will continue to say this every time I buy an old lens, but wow, they are cheap! You might as well give it a try for this price; I am definitely glad I did. Also, this lens has been going up in value on marketplaces like eBay, so if you decide you do not like it, you could probably sell it for just as much or more.
Another thing that has made me appreciate this lens is the way it has forced me to practice taking pictures manually in so many different lighting situations. If you ever slide your modern-day lenses back onto your camera, getting what you want on the first try is going to become super easy. What I am really saying is it is just a great lens to practice photography with. It challenges you in a way you have not been challenged before.
The next thing I would like to say about this lens is it really just looks cool. Most film lenses do they are antiques. It just looks awesome on any camera, and not everyone cares about that, but I certainly take it into consideration. Put this on your shelf, and you are automatically just as cool as this lens is.
Yet another one of my favorite things about this lens is the lighting you can bring out with it. It already has some golden characteristics in the glass, and if you get it out at the right times, that golden hue can be highlighted in amazing ways. I think this lens does well in lower light situations like early morning or maybe sunset because of the colors it can bring out. Just recently, I woke up early, saw the morning light shining in, and knew immediately it was a perfect time to capture this kind of lighting. I was right, and everything I love about this lens is making itself known in the photo below.

The last positive thing I want to mention about this lens is that it seems to do very well with up-close photography. This seems like it has a lot to do with the aperture settings. You cannot really get the bokeh you want out of a far-away photo because it does not really work to shoot at a 1.4 aperture from so far away. Everything normally just looks a little too dreamy and unfocused. For this reason, close-up photography can look really good because it is a lot easier to see all of the great qualities in this lens.
Here is a photo that describes the lenses capabilities well:

Notice the bokeh in the photo above. Once again the 50mm thrives in these close-up, low-sunlight situations. You have a golden hue and the bokeh I mentioned before. Although the aperture opens to 1.4, I have probably had the most success keeping it from 2.8 to 4ish. This photo and the one of the light switch were both set to an aperture of 4 when I took them.
What is not so great about this lens?
As always, I will be brutally honest with you about the undesirable aspects of every lens.
First, this is not a landscape lens. It really does not look good if you are trying to take pictures of a big field and sunset, or whatever your wide open area is. It is almost impossible to get what you want out of this lens in a big wide wide-open situation.
Second, this kind of goes along with the whole wide open landscape thing but 50mm is pretty zoomed in. This can get a little annoying sometimes. It is just not a big picture lens and if you think it is then you will be pretty disappointed when you find yourself stepping back 20ft to take a picture. For me, 50mm is not really my preference, but for a lot of people, it is. This is just something to consider.
Finally, do not let those negatives scare you away! Part of that is just going to challenge your creativity which is one of the best things you can do to expand your capabilities as a photographer. Overall, this lens is truly phenomenal and I hope I inspired someone to give it a try.
Here is another post that has an adapter guide for this lens
Trip Wayland