I do believe human-like AI is possible using non-organic electrical circuits, but I think that they'll be extremely complex and probably large and I suspect that we'll start building computers out of organic tissue in the future to make it smaller. Maybe that's just ST:VOY talking, but I think it makes sense given our own capacity (though perhaps that would sacrifice precision and so a balance would be needed to improve upon our own limitations).
I personally believe that there is nothing "magical" about life and a human being could be artificial created, albeit, it's probably far too complicated for a group of humans to comprehend without artificial help. I don't think we're anywhere near that level of complexity either. I do think it is a theoretical possibility.
I'm generally optimistic about the futures of AI. My main concerns are to do with privacy, which governments have completely failed to address, and both governments and corporations are amassing insane amounts of information about all of us. I don't believe this is in humanity's best interests, and I think it is a violation of human rights.