What is the effect of the sentencing reform act on appellate review of federal sentences?

It is common to say that the Sentencing Reform Act of 1984 (the "Act"), as amended, 18 U.S.C. 3551 et seq., 28 U.S.C. 991-98, curtailed the broad discretion formerly afforded district judges at sentencing. What is less often noted is that the Act also provided the courts of appeals with limited jurisdiction to review federal sentences where practically no such review had existed before (i.e., with respect to those sentences which fell within the limitations set forth in the governing statutes). See Dorszynski v. United States, 418 U.S. 424, 431, 94 S.Ct. 3042, 3046-47, 41 L.Ed.2d 855 (1974) ("once it is determined that a sentence is within the limitations set forth in the statute under which it is imposed, appellate review is at an end").