Some of the main tangible benefits we offer over our competition, and PhoneGap in particular:
* much faster build process (apps re-generated across 6 platforms in < 1s in the main-line case)
* unlimited support, and help prototyping your app at higher tiers: Nitobi is/was basically a consultancy based on PhoneGap whereas we see ourselves as building and licensing a software platform
* guarantee we'll never be bought by Adobe and get rolled up into Dreamweaver (not a guarantee)
* make no requirements on the IDE or other tools you use - you're good to go with a terminal and a text editor
In general, we try to be light-weight, get out of the way as much as possible, and offer a great, streamlined experience for users writing apps in the bottom 50% of the complexity spectrum.
Disclaimer: you might have guessed I work for Trigger :)