Depends on the person, and context but it's usually positive.

Many people will use it as a compliment without thinking twice of it, but it can be offensive within the context of Orientalism (specially the archetype of the Oriental sex slave, if used for a woman) and the fetishization of otherness in general. Risky adjective in a post colonialist mindset.

exotic means "not local", "something of foreign nature". Hence no positive or negative meaning. So the default is positive. for example, exotic birds, exotic foods exotic dancer = can be both, depends on context. The exotic dancers gave a great performance = positive She is nothing but an exotic dancer = negative. A nice way of saying she is nothing but just a stripper, whore, etc.

When someone is described as exotic, it usually just signifies a departure from the norm. In a situation where everyone is supposed to conform, being described as exotic is negative. In a situation where being special is better, being exotic is a distinguishing factor, thus making it positive.

It's icky. At best it's saying "you're strange. I mean that nice, but really, you're not normal. You're strange and different." That's not a compliment.