Me, too. Actually, TCoM put me off because although I loved most of it, I hated the cliffhanger ending so much that I skipped the next book. Later I picked up Equal Rites, and then after a few more came out, somebody told me about The Light Fantastic. I think a lot of Americans had the same problem with TCoM, because for years I would check secondhand bookshops and if they only had one Discworld book, that book was TCoM. I was looking because getting them in the USA was a classic case of "barefoot and uphill both ways." I found most of them at SF conventions, brought in by independent book dealers.
I think the best results I've had in getting someone else to begin reading Discworld came from choosing a book that connected with an existing interest. After they are hooked, I emphasize that the first two are a duology. I do think TCoM should be read at some point, probably before Sourcery, because it introduces some major elements.