Pros: Pancake design, can be aquired cheaply in second hand markets.
Cons: Forgettable image quality, nothing compelling about it.
My, how things have changed in the world of m43 lenses. In the early days, Panasonic and Olympus targeted much different audiences. Panasonic pursued the enthusiast market, with high quality, no compromise offerings such as their 20mm f1.7 prime & their 14-140mm zoom. Olympus went after the more entry-level consumer, offering cheaper less capable lenses, but ones emphasized convenience via collapsible barrels. All changed this year with Olympus offering 2 very desirable high end primes: the 12mm f2 and the 45mm f1.8.
That context is necessary to understand the Olympus 17mm f2.8 prime. It was conceived of as a entry level prime. When it came out, it had three selling points: it was cheap, it was small, and it was the brightest lens offered by Olympus. But all that was not enough to distract attention from Panasonic's 20mm f1.7 prime, which became the must have lens for street & natural light photographers. In fact, Olympus fans used to trumpet the combo of the the 20mm prime with an Olympus body as the only way to get a stabilized image using that lens.
Olympus began to package the 17mm as a kit lens option, and shortly after, the second hand lens market was flooded with this lens. The reason, frankly, is that the 17mm is an utterably forgettable prime. Its range was already covered by the more versatile, but diminutive Olympus kit 14-42mm lens, so the only draw was the pancake design and a half stop advantage.
I occasionally shoot with the 17mm. "Meh" I think is an appropriate descriptor. It does nothing wrong while not doing anything particularly well - the lens is ok sharp, is ok bright, produces ok colors. Meh. In the m43 world, lens distortions and aberrations are corrected by the camera itself, so it is a tad bit difficult to judge the quality of the lens, but I detect a light barrel roll distortion - frankly something I enjoy- and a tiny bit of chromatic aberration. The AF speed is a tad bit faster than the 14-42, but I have an older e-pl1 body, and wonder if the new faster e-p3 could do much better AF wise with this lens.
The plastic silver painted body feels & looks cheap. It does not have filter rings. It's small and light as a pancake lens should be.
I shoot with 17mm when I want my lightest, most portable config on my camera - such as when I'm walking about town or flying with the camera on my carry-on bag. Effectively, a 34mm lens, I enjoy the focal length - versatile for the streets and enough to justify bringing my camera in the first place. But I don't pretend that as a prime, it is bringing anything special to the table.
Which brings me to my tepid recommendation. The second hand market is still flooded with this lens - and for half of retail, you'll get a pancake lens that will work its way into the lens rotation, if only for reasons of portability. In most cases, it was an unwanted kit lens, never used. But if you're thinking of paying retail, I would strongly advise paying a little bit more for the Panasonic 20mm prime - the f1.7 makes it a much more versatile purchase.