I don't use Mexican vanilla, so I don't know about a cinnamon taste, but just be aware that some of the "vanilla" extract available in Mexico isn't really vanilla at all, but an extract from the beans of the tonka tree.
"Tourists tempted to pick up bargains south of the border should beware of one bargain that isn't a good buy—a so-called “vanilla” flavoring or extract that isn’t vanilla flavoring or extract at all, but instead is made from a completely different plant material that contains coumarin. Coumarin is a substance with potential toxic side effects banned from food in the United States.
This flavoring product may smell like vanilla extract, taste like vanilla extract, and be offered at a cheap price, but it could present a significant risk to some people’s health.
Pure vanilla flavoring and extract are made with the extract of beans from the vanilla plant, a type of orchid that grows as a vine. The product containing coumarin is made from the extract of beans from the tonka tree, an entirely different plant that belongs to the pea family. Tonka bean extract contains coumarin, a compound related to warfarin, which is in some blood-thinning medications. Eating food containing coumarin may be especially risky for people taking blood-thinning drugs because the interaction of coumarin and blood thinners can increase the likelihood of bleeding."
-from the FDA website on Mexican vanilla,
http://www.fda.gov/forconsumers/consumerupdates/ucm048613...