The simple fact that the 40D is slightly larger than the 20D, yet slightly smaller than the 5D was a selling point for me. I have large hands and need a camera that I can grip without it feeling like a small toy. It just seems to have a bit more "heft" I guess you could say. The partial weathersealing, finger groove beneath the shutter release, paintless hotshoe, are all really nice little bonus physical features, and I love everything about the new menu screen, very much like the 1D! And though the larger LCD wasn't a big deal for me when I first heard about it, it is indeed a very welcome feature. I've effectively put Live View to use and it definitely has a place on a DSLR despite how some may feel about it. I think this will be a very useful tool for a lot of shooters, and it was well implemented IMO. I really like the fact that I can change focusing screens and I will definitely be ordering an Ef-S super precision matte. The AF-ON button is also a great addition, though some may prefer to still use the good old fashioned * to separate the metering from the focusing. The good news is Canon gives you the option to go either way and doesn't force the AF-ON down your throat if you don't want to use it. Thanks, Canon! I found that the IQ is typical of any Canon camera, which is a good thing, and it handles noise at high ISO very well. The high ISO shots I took at a recent wedding were very usable and cleaned up really well with very little NR applied. Colors are vivid and bright, and there's a somewhat warmer feeling to the images. I can't quite put my finger on it, but the images are very 5D like in quality (without resorting to pixel peeping). The DiG!C III processor does a damn fine job and I'm satisfied with the quality of images this camera is capable of producing. AF tracking seems to be spot on. I was taking sample shots of oncoming traffic during a fund raising car wash we were having, and this system did not disappoint! For those of you who are concerned about it, the AF tracking works and it works well. And who can complain about a max burst of 6.5 fps, a couple of extra megapixels, an improved buffer (up to 75 jpegs!), automatic ISO, ISO viewable in viewfinder, being able to view selected AF points during playbck, the ability to register up to three camera user settings, 14 bit AD conversion, improved metering and spot metering range, extended Kelvin WB temperature range, brighter viewfinder, multiple exposure mirror lock-up, and a self cleaning sensor? All of which are great little goodies that only compliment this already great camera. And sRAW could definitely come in handy for some applications. Again, I've put this feature to use and it does become very useful when you want to shoot RAW, but have limited memory or don't need super large files to work with. Accidentally erasing all images on the card has been mitigated by having to turn the feature on in the menus, or batch check marking, which is a good thing if want to avoid inadvertently wiping your card clean! And among one of my favorite new features is the common sense and simplicity applied to what functions are assigned to the buttons near the top LCD. Metering is now paired with White Balance, Auto focus with Drive method, and ISO with FEC. Trust me, it makes much more sense this way. The new button layout beneath the LCD was not difficult for me to adjust to, though I must remember that the menu button is still located on the top left corner separate from the rest.
A few things that I could do without are the direct print button, the plethora of automatic Basic Zone shooting modes, and the plastic battery compartment hinge (why they did away with the metal hinge is beyond me - to cut cost
) One minor gripe is the Picture Style button. I wish it was programmable in custom functions so that you can use it to either select Picture Styles, or access the Image Quality or White Balance setting menu like on the 1D series. Not saying you can program those buttons on a 1D, but those buttons are made available to you on the body in a convenient location near the rear LCD.
In short, this may not be the "Wow" factor some folks have hoped for (it certainly is for me), but for what you get for the money, it has really impressed me and is definitely something that I'd consider a great improvement over its predecessors. Not trying to convince any happy 10/20/30D users either way, but just know that there is much more to consider than just what you see on the surface. 
. If i like it i buy it, simple as that. 
