As you would expect, this museum is a solemn experience. It does a very good job of documenting the history of slavery, and the people involved in its creation and abolishment. The last wing is a very good exhibit relating the past to the present slave practices in today's world. This entire museum is a must-see for people that have the maturity and patience to learn and reflect. The exhibits are varied, interactive and engaging but I do not recommend this stop for children. It really does need some amount of concentration and reflection. We were fairly tired, and emotionally and mentally drained after about 3 hours (we probably needed 4 hours to see everything completely). The architecture of the building is purposefully light, hopeful and open. Really beautiful.
Even though the audio map and the ticket takers suggest you start on the second floor, I HIGHLY recommend you start on the third floor in the "From Slavery to Freedom" gallery. It is an excellent summary of everything presented elsewhere in the museum, plus it is the most compact and interactive review of the history. Many of the other exhibits in the museum repeat or explain further what is in this gallery. After this first stop, you will be ready to go down to the second floor to see and appreciate the centerpiece of the museum and the other exhibits. End your tour back on the third floor in the Perseverance gallery. After touring the whole exhibit, everyone in my group agreed this would have been a more logical way to absorb and appreciate the information presented.
There are excellent movies through the various floors. The first movie, though, in a beautiful main theater on the second floor ("orientation") is the least helpful or engaging of any of the presentations. You won't miss a thing if you skip it.