Firstly, it is incorrect that the camera has the same image sensor 400D as the Eos. While the resolution is the same, but the sensors structured differently, so that the 40D with the same resolution through improved microlenses on the sensor has less noise. Various sensors, so much so.
On the other hand, the case that by the previous speaker with "can deal with difficult weather conditions, without being damaged." is referred to, not as weatherproof as it is now presented. Anyone who reads the Canon product information carefully, notes that there is only that the dust and water tightness has been improved on the memory card and battery compartment covers - with a small foam gasket, no longer. Real splash protection is guaranteed only with rubber seals and even if all major ports of the camera are sealed. However, this is, for example, with the many buttons, the lens mount or the hot shoe is not the case.
The camera keeps dust even better than its predecessor of memory card and battery remote, real splash holds but that did not stand. Although the camera does not in the first few drops have damage, but can not with "difficult weather conditions" deal and should as far as possible be kept away from rain or other splashing or very large dust.
This should be considered when purchasing, reduces for me not very the value and quality of the camera bodysuits. For me decisive for the point deduction for maximum rating is the botched ISO Auto, the unnecessarily high ISO values used in the standard case (default ISO 400) and therefore is not available for me in most cases.
The positive points I need not repeat well as have been summarized otherwise already beautiful in recent reviews.