Economics 1010a is really Ec 10 with more curves to learn, no reading, and a teacher who might actually know who you are. It was previously taught by Jeffrey Wolcowitz, a rotund policy wonk who makes an effort to help his students and learn their names, even in a 300-person lecture class. Jeffrey A. Miron takes his place this year.
In addition to what you learned about monopoly, perfect competition, and positive and negative externalities in Ec 10, you'll draw stranger graphs that look pretty in your notes but won't make conceptual sense to you at all. If economics is your love, you'll probably get caught up in the 1010a spell. Otherwise, you'll stop going to lecture.
Problem sets are pretty close in difficulty to exam questions, as long as you actually try to figure them out yourself and don't rely on your TFs or smart friends to work through them with you. Ha Yan Lee is a Diet Coke-addicted, candy-throwing, funny and frighteningly well-prepared TF whose review and problem set help sessions are always crowded.
Unlike Ec 10, you aren't in the least expected to do the assigned reading (i.e., you don't have to even pretend to apply economic concepts you learn in 1010a to the real world). For better or for worse, that and other aspects of Ec 1010a make this class a more technical and in-depth version of Ec 10.