Great museum, many different types of work. Could easily spend 45min-1.5 hrs looking at it all. My only complaint is that the audioguides available for purchase only have a few rooms translated, its not worth the 500₽ they currently charge.
From the capital it is a long trip. Guatemala city to San Marcos, San Marcos. From San Marcos to Tajumulco ( Hotel villa real). An approximate six hour hike to the camping area, followed by Another one hour to the top. A bit littered with trash and path is not easy for beginners, but the view above is worth the trouble.