Since nothing of substance has been presented to refute Dispensationalism, it is the opponents of Dispensationlism who have been getting hammered (through self-inflicted wounds).
No serious student of Scripture can deny that God has been dealing with humankind at different times in different ways, but all those who believed God since Abel were justified by grace through faith (Hebrews 11).
Also, no serious student of Scripture can deny that only certain portions of the Abrahamic Covenant have been fulfilled, or that the Rapture of the Church has always been imminent, or that the second coming of Christ will be preceded by the Great Tribulation followed by a stupendous shaking of the heavens and the earth.
What is frequently lacking -- and this is shocking -- is the absence of total honesty by those who attack Dispensationalism. Therefore they resort to ad hominem attacks on genuine Christians such as Darby, Scofield, etc.
Also, while many evangelicals and fundamentalists hold to Dispensationalism, everyone is not in total agreement about everything (and this is not necessarily an issue). For example, many Dispensationalists believe that there was a "Dispensation of Innocence" (Genesis 1 & 2). Well the impression we receive from Scripture is that no sooner had God settled Adam and Eve in Eden than Satan entered into the garden and ruined everything. So was this really a dispensation? The word "dispensation" is equivalent to "stewardship" but we see no stewardship by Adam whatsoever.
Also some Dispensationalists believe in the Gap Theory (a period of time between Genesis 1:1 and Genesis 1:2), but again, there is no evidence of any such gap, or any other creatures on earth before the six days of creation.
However, the fundamental principle of recognizing different covenants (and their related time spans) as different dispensations is sound, and there is no question that Revelation is progressive. That is why we see the tree of life on earth in Genesis, but the same tree of life in Heaven in Revelation. We see the Ark of the Covenant on earth in Exodus and the same Ark of the Covenant in Heaven in Revelation.