Isaac was a contemporary of Josquin's, but this isn't entirely obvious from the music itself. He organizes the sections of his Mass in much the same way that many late Medieval and early Renaissance composers did, using full cadences a bit more often than a later Renaissance composer would use. At times, too, he gets long winded, but then at the last minute treats the last few words of a phrase in businesslike fashion. The third Agnus Dei is a good example of this.
All the same, the harmonic language is practically straight up F major, and the melodic figures are not as challenging as they'd be in a Mass by Josquin, Taverner, or Dufay. In fact, there is a great deal of homophonic writing. Moreover, the Mass isn't nearly as long as many others from the same time period. In short, it seems that Isaac was composing a bit ahead of his time. This Mass is a good choice if you're looking for accessible repertoire from a period that's a little earlier than most ears can handle. Maybe it's even one of those bridge pieces that opens up doors for people (if I may be permitted to mix metaphors).
This Mass looks scarier than it is, and I promise to let everyone know if I ever get around to making a more practical version. (If someone else wants to do it, by all means, I won't stop you!) If a choir has the right voices, that is the biggest hurdle. Beyond this, the Mass pretty much sings itself.