C.Z.
The switch was pretty easy for us except he will only drink milk slightly warmed. Formula he would drink cold, warm, etc., but cow's milk has to be warmed or he takes two sips and hands it back to me. We also switched to sippy cups at the same time; he was already drinking water and juice from sippy cups, but would only take formula from a bottle. We do have to use a different type of sippy cup for milk though - for juice and water any sippy cup works for him, but for milk is has to be a sippy cup with a soft spout (similiar to the bottle nipples).
Good luck!