I am looking for a prime lens on GH2 that will work in the following situations:
a. General purpose family video (60%) and photo (40%), without tripod or frequent flash.
b. 60% percent outdoors and 40% indoors.
c. being as portable and inconspicuous as possible, preferably pocketable (being able to fit inside a large pocket or waist pouch).
d. not spending the money if the benefit is marginal.

I would like to have OIS (I would be willing to pay for that), but it looks like none of prime lenses(not even other manufactures) has it, for reasons I don't understand. Do they still think primes are for photo only?
Anyway, based on the criteria, it looks like pancakes 20mm 1.7 and 14mm 2.5 would be good candidates. I would be interested hearing about others too.
I read on the net that 20mm focus is slow and noisy. That would be a big downside for me as I would be using AF all the time. Of course I love the bigger aperture of 20mm, but how bad is its focus compared to 14mm. Another factor is price, 20mm is still $350 (on Amazon/ebay) while 14mm is less than half price at only $170 new (on ebay).
So, given pros and cons, and for the purposes I am using it for, which prime lens would you recommend?

My preference in order:

#1 Panasonic 45mm Leica f2.8 with OIS
#2 Panasonic 25mm Leica f1.4
#3 Panasonic 20mm Pancake F1.7
#Last possible choice Panasonic 14mm Pancake

The 45mm is my go to lens and my all around fav on my GH1. The 14mm, I have had that 3 different times now and just don't like it, YMMV. The 20mm is slow and focuses kinda weird for video. The 25mm is sharp as a tack, but lacks the OIS of the 45mm. Oly has several nice lenses but none will offer OIS on a Panny body. People are saying the Oly 45 f1.8 is a must have and also many love the Oly 12mm f2.

I have found that for doing stills, all the Lumix glass has correction built into it and the camera. This just about completely eliminates any CA and other issues I have had with other lenses.

Lee - my opinion is a little different from Chip's.

I've shot with the 14mm and I like it - small enough to fit in a coat pocket with the GH2 - and it's good value for money at $279. It also has silent autofocus - and is fast enough and wide enough that you don't really need OIS.

If you shoot video and care about autofocus noise, don't get the 20mm.

My second choice for your needs would be the $590 25mm f1.4. Not really pocketable, and fairly expensive - but a fabulous lens on the GH2.

My third choice would be the 45mm f2.8 that Chip recommended. Yes, it has OIS, but it's pretty expensive at almost $800 - and the longer focal length (90mm equivalent) can make it a real challenge to capture the entire scene indoors - especially in small rooms.

Hope that's helpful,

Bill
Hybrid Camera Revolution (http://hybridcamerarevolution.blogspot.com)