Well, I don't have either lens, so FWIW. The 17 f2.8 gets, to be polite, very mixed reviews. Some user reviews are very positive but overall it gets pretty poor reviews from most review sites. I've wondered about quality control and if there is a lot of copy to copy variation? The 17 f1.8 is 1.3 stops faster, that's significant. Having a fast, normalish or slightly wide effective focal length lens will really open up a lot of opportunities for you when added to your kit lenses. I have the PL 25 f1.4. The fast aperture is really an asset in many situations (the 2/3 stop difference between the 25 and 17 is not so huge, IMO). Used with the IBIS in the E-M5 I've gotten very useable images shooting handheld in situations where the kit lens wouldn't have come close. I'd like to pick up the 17 f1.8, though it's hard for me to justify given that I have the 25. Sometime maybe. I'd say go for the f1.8 lens.