I've been using the Milwaukee 2420-22 Hackzall kit in my remodeling and deck-building business since late last summer. Designed for light cutting, this miniaturized recip saw takes the same 12-volt lithium ion batteries that the M12-series screwdriver and impact driver use. The Hackzall has a grip with an unusual shape. It looks more like a drill's grip than a recip saw's. I liked the tool's comfortable feel and handy size right away. It's small enough to use in tight quarters where a full-size model wouldn't fit, and I can stuff it in a toolbelt when I'm climbing a ladder.
The saw has a variable-speed trigger and an LED task light that shines on the work area, and comes in a blow-molded case with a 30-minute charger and two batteries.