What a GREAT museum.
We went today for Free First Sunday. (Every month there are three museums in Mesa that offer free admission on the first Sunday of the month - sponsored by Target). It was pretty crowded but we managed with no problem. The exhibit halls are very well done. There's a little something for everyone - dinosaurs, space, mesoamerica, Arizona in the movies, panning for gold, replica pueblos, walk through jail, archaeology finds, etc.
I was impressed with the staff as well. They were friendly, helpful, knowledgeable and plentiful.
We really enjoyed our visit. Great place for the entire family - everyone is bound to find something they enjoy. My 10 yo daughter and 12 yo son enjoyed it equally and are already looking forward to returning!