I'll be curious to see what you think about the optical quality as well as the build quality.

Piqued my interest, so I wanted to compare to my OM-2 (body for body). Not necessarily apples-to-apples in functionality (esp autofocus, autowind, and integrated flash), but both small, light SLRs of their respective eras.

*ist (per B&H site):
Dimensions 4.8 x 3.3 x 2.5" (122.0 x 84.0 x 63.5mm) WxHxD
Weight 11.8 oz (335g)

My OM-2 (per www.mir.com):
Dimensions: 5.35"x3.27"x1.97" (136 x 83 x 50mm)
Weight: 18.3 oz (520g)

So the *ist is a perhaps a bit more compact (depending on whether you favor width over depth or not), but much lighter.