After sort of moving to zoom lenses for most of my work, and only the 60mm macro as a prime, I rented the 85mm f/1.2 recently. While this lens is very much beyond any kind of reasonable price that I could ever justify, it got me interested in both primes, and the focal length again. I liked the ability to be a bit further away and get less in focus compared to my 60mm.
As well, when comparing the 135mm f/2 and the 85mm f/1.8 the depth of field difference was there, but not something I thought I would notice a lot if framed right. As well, when I rented the 135mm I found it nice, but a bit long for most use on a crop sensor camera. At the same time, I became convinced I would appreciate the 35mm f/1.4 L lens as well, but couldn't justify it, either. As mentioned previously, I ended up deciding on the GF1 instead of the prime lens - and I've been happy with that decision.
Then I found a refurbished 85mm f/1.8 and decided to give it a go. Since the alternative at 85mm in the Canon lineup is so outrageous, and even the 'cheap' 135mm is three times the price, I'm happy to have found a decent prime lens that should get some use. Here is a recent stock image taken with this lens. I like the out of focus background, and even her ears are showing some blurring at f/2...
One thing I haven't quite understood with primes is that they often seem to have poor results in tests wide open. One wonders why you would pay for such a lens over a zoom if you "can't" even shoot wide open with it. And there is the problem - the reviewers often ask the wrong question. They are asking how well does it perform taking shots of a black and white, high contrast target in bright light - what they get is a bunch of CA and fringing, and general lack of contrast. If you actually take such a lens and shoot in the kinds of conditions where you want a fast lens, you find that it performs admirably. Hence why there are so many reviews that primes aren't great, not sharp wide open, and then a whole bunch of people using it for professional use and swearing by it. You need to actually use it to rate it! How often will I shoot back lit leaves with this lens wide open? Never! How many wedding shots are blurry, slightly soft, but absolutely loved because they captured the emotion?