[Batfish]

I bought the Dremel Lithium-Ion rechargeable about 7 months ago and I love it. You can't use all of Dremel's attachments with it, which is the only real drawback. Things like their drill press attachment may not fit. All of the normal bits fit it just fine, though.
If you get a corded one, my only recommendation is to get one with the most variable speeds. If you're cutting a bunch of different materials (steel, aluminum, plastic, wood) it sucks having a rotary tool with only one or two speeds to work with.