It's not only a lot stronger (approximately double the strength of the same dose orally) but feels almost like a different drug, in my experience. If I want mellow I'll plug it, if I want Technicolor "K-Hole" (of sorts) I'll snort it. I do generally snort it kut with ket though which probably adds to the whole K-Hole thang :D
2C-C and 2C-D are the only 2Cs I would sniff. 2C-D cos it doesn't hurt too much and doesn't seem to adversely affect the trip, and 2C-C cos I prefer the effects sniffed. All other 2Cs are definitely oral or rectal only for me.