It comes pre-packaged and set up, with integration for the market (of questionable value) and Motorola emulators (fantastic - the more test targets the better).

Downloading Eclipse+ADT separately wasn't too hard last time I did it, but it's always nice to have steps removed. Most handset/java (Android, RIM, J2ME) developers I know have several Eclipse installations on their machine anyway to stop plugin conflicts so having one more is no big deal.

(EDIT: They have also removed Linux support, which seems to be an odd decision to say the least.)

They also have code snippets and Application Creation wizards. I think the later will be useful what with the api still being unstable(pmi pkg disappearing between 1.0 to 1.5 etc).

The one from Motorola does not run on Linux.

It is eclipse.