The concept of federalism in the United States is essentially the division of power between the centralized federal government and the individual states. Since the middle part of the 19th century, a power struggle has occurred between these entities, with more and more power gradually shifting to the federal government. A large part of this was the result of decisions made by the Supreme Court under Chief Justice John Marshall that were favored expanding federal power and paved the way for even more expansive New Deal policies under FDR.
Many notice this shift continuing today, and critics warn of serial infringement on the 10th Amendment to the Constitution, which states that any "powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people." In other words, the federal government has only those rights referenced in the Constitution. Furthermore, none of these rights can violate the natural laws and rights of man.
The term devolution typically refers to the delegation of power from a higher authority to a lower one, such as by a central administration (the federal government) to a regional one (the states). While this idea lied at the heart of the country's founding, it certainly has not been the common practice over the last 150+ years. Contemporary federalism has strained to retain, or better yet regain, true devolution through the court system, as federal power continues to usurp that of the states whenever it's deemed appropriate, especially at a time when modern technology has made interstate commerce and other such relations so prevalent. Evidence of this can be seen through the never-ending codification of federal laws.
Whether or not one agrees with the idea of devolution is purely subjective in nature and requires a serious look at the pros and cons of it as evidenced by its application (or lack thereof) in various societies around the world. If one sees more benefit in millions of people acting autonomously to further their own self-interests, then devolution would appear more meritorious. If, on the other hand, one sees more benefit in a small contingent of representatives engaging in central planning based solely on what they feel is best for the people, devolution may appear lacking.