The E-10 is Olympus's foray into the professional digital SLR market, it's also priced to tap into the lucrative prosumer market where owners demand the best quality and features. Looking a little like Sony's DSC-D700 the E-10 has a fixed 4x optical zoom lens (with real mechanical zoom and fly-by-wire focusing), a true TTL viewfinder which gets its image from a beam splitting prism placed between the lens and CCD. The 4 megapixel CCD makes the E-10 the first true 4 megapixel digital camera available.
Olympus have clad the E-10 in a strong metallic case which gives it a very robust and professional appearance (the last time I held a case this good it was on a D1), the deep hand grip, protruding viewfinder eyepiece, progressive squeeze shutter release, rolling command dial and generous sprinkle of high quality feel buttons let you know that this is no ordinary digital camera, real Pro design, features and build quality.
The E-10 features a unique prism for splitting the image the lens is projecting simultaneously between the optical viewfinder and CCD. This allows for both a TTL viewfinder view and live video feeds from the CCD and thus a "real image" view using the rear LCD display. It also means that the E-10 has very little shutter noise (no mirror flip), to compensate you can (god forbid) enable a simulated shutter sound (just like a Sony Mavica).
Olympus also make some very valid points for fitting out the E-10 with a non-removable lens. It helps to combat several problems: (a) dust, digital SLR's are renowned for requiring regular cleaning of the fragile (and expensive) CCD sensor as it tends to accumulate dust and dirt (which appear as dark smudges on final images), (b) lens quality, because the lens was designed to match the camera it's quality tends to be better than many off the shelf lenses designed for (less critical - larger sensor area) 35mm SLR's and (c) focal length multiplier, again because the lens was designed for the camera it's focal length is designed to match the sensor. It also makes the camera smaller and neater than many digital SLR's based on film body designs.
Having said all this I can't really say I sit on either side of the fence, I like the idea of removable lenses on SLR's because it does give you an added amount of flexibility and better upgrade options, but I hate the dust problem and until manufacturers can solve that one Olympus's compromise seems to be a logical one.