While the H1 appears to support JavaME, it looks like Vodafone is pushing widget development as the primary way to develop for the device. This follows on from Vodafone's Widget platform for Symbian S60 devices and current widgets should run with few if any changes on the H1 (the biggest difference widgets face is the difference in screen size).
Widgets written for the H1 can be sold through the Vodafone 360 service's app store and can also appear in the app stores of Verizon, SOFTBANK and China mobile thanks to the efforts of the "Joint Innovation Lab". JIL have released an SDK for Linux and Windows (with the Mac somewhere in the pipeline). It would be interesting to compare JIL's widget SDK with LiMo's Widget SDK (called BONDI), as the H1 is a LiMo phone.
I didn't make any calls with the phone, so I have no idea about call quality. The thing that impressed me most was the quality of the (touch) screen - which has a surprisingly high resolution of 800x480. No idea if it supports multitouch (if it does, I didn't stumble across anything that used it). One odd screen related thing that was noted during the presentation is that widgets can't switch to landscape mode, at least not easily. They showed Bloomberg's widget (apparently a port of their iPhone app), which does go into landscape mode (I'm guessing through CSS tricks), however the chrome around the widget remains in portrait mode (so it looked a little odd). It's certainly something I'd like to see fixed in the future
I have an odd feeling that the VF360 Samsung H1 shows us what Samsung's newly announced Bada platform is going to look like - something "flashier" than a featurephone but not quite as powerful as a full blown and more expensive smartphone. The H1 is a LiMo device with a WebKit based browser - we should find out soon if Bada phones are Limo/WebKit combos as well.