For anyone contemplating the move, here are some of the pros and cons I have found after 2 weeks of use of the I300 and about a year's worth of use of the Prism/Minstrel.

Pros for Prism/Minstrel:
- SUPERIOR screen quality compared to I300
- Noticeably faster data speeds (max of 19.2)
- USB hotsync
- unlimited use/access (Omnisky)
- larger screen

- brick-like
- extemely finicky signal (easily lost)
- modem is buggy and can cause fatal errors/hard resets
- screen is totally washed out in direct sunlight
- carry two devices (cell phone)
- combo requires 2 chargers
- if not charge regularly, can end up with powered PDA and dead modem or vice versa, either way makes combo useless until can get to a charger

Pros for Samsung I300:
- obviously, only have to carry around ONE device
- drastically improved data coverage, more coverage and signal is not as finicky as the Minstrel CDPD signal, can move around freely and not lose signal (inlcuding at 70mph+ in a car)
- screen is not totally washed out in direct sunlight (somewhat useable)
- combo is very stable, haven't required hard or soft reset yet!
- one bill for voice and data
- phone can be used with included cradle as wireless modem for laptop right out of the box!
- only one charger
- if battery low/dies, simply pop in the extra included one and you're good to go, no need to worry if both PDA and modem have enough juice

- serial hotsync
- somewhat (but definitely noticeably) slower data speeds (max is 14.4)
- significantly smaller screen, colors are definitely not as vibrant (not even close) as Prism's (IMO, screen is better than M505's but not better than IIIc's)
- no keyboard available yet
- data calls come out of voice minutes so no unlimited use (bad for things like wireless avantgo syncs or wireless hotsyncs)
- depending on use, battery only good 1-3 days

If you are tired of carrying around two devices and are willing to make a few concessions (mainly screen real estate and quality), would definitely recommend the device. For me, the ability to actually keep the data signal while moving around (walking) instead of having to search for the signal (and then lose it once I find it) more than makes up for the I300's screen (which is pretty average for a color screen).