I'm not a professional photographer/videographer but... I've been in broadcast TV since God was a boy. I'm now in broadcast TV production (in a small way). We a complete Beta-SP edit facility and find it neccessary, at times, to shoot with our Beta-SP camcorder with a standard issue ($1,500) and not-high quality lens. Also, I have been through a series of semi-pro camcorders from VHS to VHS-C to Panasonic's AG-EZ1 and now the XL1.
After shooting half a dozen cassettes under a variety of conditions I can say that in my experience:
Much more than just occasionally the pictures (when played back on Sony DSR-60 and viewed on a full component monitor) rival Beta-SP for color, resolution and overall quality. I have no personal experience with the Sony competition but I can tell you the XL1 (I assume, largely because of the vastly superior "glass") shoots rings around the AG-EZ1. There's no comparison.
I'm used to manually white balancing every shot. The auto white balance on the XL1 is incredibly good. I have come to rely on it under all but the most bizarre lighting conditions. It was almost always right on.
The optical stabilization is absolutely awesome. As you probably know, Canon's pro lens with a similar system list for almost $25,000. To the eye, at least, the picture damage is zip and I leave it on almost all the time because it's much less heavy handed than the digital systems. I love it. At 16x zoom, it's still hand held but it's the best hand held I've ever shot. At mid zoom ranges I could come close to rock steady.
At least by the time I got mine (February) the viewfinder picture is extraordinarily accurate as to color and resolution is great! I have no trouble determining, for instance, when I need to manually white balance. On the other hand...
The worst drawback... easily... the viewfinder's extraordinary sensitivity to sunlight. I suspect Canon will be relacing every viewfinder, probably more than once. No matter how careful I was (during a recent Caribbean trip) since 90% of shooting was done with the sun at my back... it was impossible not to lift my head (let's say, to find the right one of those 99 buttons on the side of the XL1) and zaaap! I have multiple yellow burns on the viewfinder. Canon says, send it in and in a week they'll asess and repair under warranty. I inquired about buying a backup viewfinder and was told: not available. They need to go to a B&W finder or come up with some sort of shutting system or at least make available a reasonably priced back up.
The second worst drawback... I've never owned a camera that was less user friendly to hold comfortably for a long time. I found I was shooting with one hand underneath and the flip down shoulder pad flipped up and stored. I'd say I used the SP-100 shoulder pad, that is, shot with it the way Canon envisioned, about10% of the time.
Because the focus and zoom are meant to be powered... they stink manually. No big deal for me. The button pressing auto-focus feature is a big plus. Used it 90% of the time. Never used auto focus. Never used manual zoom except to set focus and save batteries (the Watchdog notes: these are common trademarks of pro shooters).
Auto focus and the focusing button seemed a bit squirrely. Sometimes they just didn't work. Sometimes I'd zoom in. Focus... youch the zoom and get instant soft focus. Could find no pattern of when or why.
The bottom line... for my purposes and given my additional equipment (component DV player, etc.) I'd buy the XL1 again in a heartbeat but it's certainly not for the casual user. The best pictures come with a price. It's far from the easiest or most comfortable camcorder to use. Oh, on my Caribbean cruise trip, it was the bell of the ball. From the ship's crew to St. Thomas store keepers, I was constantly having to explain the XL1... so any pros who think they can go low profile with this DV cam had better think again. It attracted much more attention than when I travel with the Beta-SP full-size camcorder.