The states of the South seceded from the Union because they felt that the federal government was trying to exercise too many powers and to take away their rights as sovereign states. Therefore, it is not surprising that the constitution of the CSA emphasized states’ rights. This is what is most striking to me.
One thing that is just of interest, but not necessarily striking, is that the CSA kept the three-fifths rule with regard to how slaves should be counted for the purposes of representation in the House of Representatives. This is interesting because it shows that some states in the South had fewer slaves than others and did not want to let the other states have more power.
Most striking however, is the fact that the CSA constitution has so many aspects that limit the power of its central government. There is no clause about the national government having the power to provide for the “general welfare” of the country. The preamble emphasizes the “sovereign and independent character” of the states. State legislatures are allowed to impeach federal officials who serve only within their state. What all of this tells us is that the states of the South were very eager to guard their own rights and sovereignty. This is what is most striking to me about this constitution.