Quick impression list:
-Very compact
-The spec says 3 hours of recording time per charge. Not too shabby
-34x optical zoom
-Built-in lens cover, but operation is manual, not automatic
-Tripod hole
-Affordable price
-Uses the standard SD/SDHC cards
-Uses H.264 instead of MPEG2
-Can record in widescreen mode (720x480)
-Interval recording feature! (see below for video)
-Uses standard USB mini jack
-Widescreen mode recording is interlaced. iMovie and Quicktime have problems with it. Luckily there is a freeware for Mac called JES Deinterlacer. Still, this requires an extra step and encoding during video editing. Annoying and time wasting.
-Video quality is not the greatest, but since the final destination is youtube, I don't think it's a big deal. AVCHD video takes a LOT of space, and if the end result is youtube/DVD, IMO why not just use a standard def camcorder.
-Minimal accessories included (AC adapter, A/V cable, USB cable, pouch). Based on the manual, there will be models that include built-in memory (8GB and 16GB), and docking station.
The interval recording feature is awesome, and fun! You can basically set the MX20 to record an image every second or longer. The movie itself is still 30 frames per second, resulting in a video with a fast forward effect. This is used to be something only a pro can do, and/or very difficult. Now, it's automatic. Here's a video I took:
In short, I think I'm going to like this camcorder, especially for the money.