The 18-megapixel EOS 100D is the literally smaller brother to the 700D sitting at the summit of Canon's APS-C sensor incorporating DSLR range. Indeed, the sales pitch for the 100D is that it is the world's smallest and lightest DSLR at the time of writing.
Smaller and lighter build makes carrying DSLR body and lens less of a drag; yet more compact proportions haven't obviously compromised picture quality
The lighter construction results in more obvious camera shake in lower light; no angle adjustable LCD plus a smaller handgrip than the 700D which costs just 50 quid more