All three Zuiko 28's are very good lenses. As I recall, there is some slight variation in tonal rendering, but they all give excellent results. The f3.5 is often poo-pooed as a "slow lens" and as such is very inexpensive, but is a good performer with a respected reputation among Zuikoholics. And it is tiny, even by Olympus standards. I have taken landscape shots with a flower within inches of the lens with everything in focus to infinity, and gotten great results. Even the f2 is small by comparison to other manufacturers. The three 28's and the 24f2.8 all fit into two regular pockets in my lens case.
Like any Zuiko, the 24f2.8 is a very good lens. It got some use in a trip to Cambridge where restricted space inside buildings and along higgledy-piggledy streets made framing very difficult. Personally I find 24mm difficult to use. Large, close objects end up being distorted and distant objects just get lost; it is the high end of the "gimmicky" wides where you trying for an effect and not a realist photo.