It handles really well. The start-up time is a wee bit slower than the a12 50, but not much, and AF is noticeably faster. I also think low light performance has improved somewhat, so while the lens is slower than either previous ASP-C module, having to sometimes make an early jump up in ISO doesn't hurt as much as I thought it might.
And the new lens is even more quiet than either of the previous a12's, which is really cool. Basically only a slight buzz when you power it on or off and slight motor noises when zooming, but that's about it.
I love it so far. If it had some better was to manual focus it would be perfect, but as is I've never had a problem with the AF so maybe it isn't that necessary.
Oh, night pics. Oops. I'll have to post some ASAP.