not my first prime but my favorite one and my favorite lens for portraits, street. i don't do lens reviews (this is my first one) but it's such a great lens that i have to back up everyone on this thread. this lens is a pure treat. you'll find excuses to bring it along for every photo trip/outing.
i sold my 70-200 2.8 IS I to fund this. some days, i miss the versatility but the IQ is so good, i've never looked back.
the color and bokeh set this lens apart from anything else (although i haven't tried the 85L). the sharpness is great, even wide open. i use it at f/2.2 mostly. you buy a lens like this for use between f/2 and f/2.8. the background blur is truly outstanding. otherwise one of those white zooms will suffice. it's black so it's lower key, it's not heavy like the zooms, and you'll end up zooming with your feet to show off the IQ of this lens.
a lot of talk about making this an IS lens. that's fine, but if any of the IQ is sacrificed in doing that, i'd recommend against it. you don't need it, people have been taking incredible shots with the lens for years without it.
considering many other L primes cost much more than this, i think it's the best value of the canon trinity and the entire L lineup.
while i could trade out some of my other nice glass, i'll never get rid of this one. at least rent it to see what the hype is all about...