In most cases they can be interchanged. But the first one people use when they assume you like the object in question and want your opinion on it. The second case is used if they want a general opinion, so it can be a positive or negative opinion.

Hello Helen, I don't think they are interchangeable. I would use 'How do you like ..' when I offer someone something (a drink - for example). I would expect an answer like milk and 2 sugars. 'What do you think of .....' is asking for an opinion. "What do you think of Operatic Metal?" Hope this helps Bob