Despite some of the snarky comments, swaimj does make a good point when asking what things the OP finds problematic in Pentecost's work..?
I would add that Dispensational Theology is like any other theological system -- it is a construct to understand the revelation of Scripture, but is not insipred in itself. Also, finding the writings of one particular Dispensationalist problematic does not mean every other Dispensationalist is wrong -- or that he/she agrees with Pentecost.
For instance, I find the "Left Behind" series of FICTION to be interesting entertainment, but there are several theological flaws. Don't look to them for a consistently good example of "Dispensational Theology." And remember, Dispensationalists are just human -- JUST like all the theologians that hold to other perspectives -- so, none are perfect, nor will we agree 100% with every one on every issue...