The last four hundred pages of this are fantastic; vintage Clancy with geopolitical intrigues, human frailties, military action and a classic hero in the form of Jack Ryan.
But the first 600 pages of the book are fairly heavy going - about three important plot lines are set up but unnecessarily slowly given the huge drama when they finally come to something in the finale; there's a lot of tedious technical stuff about submarines and nuclear physics which went way over my head; and a lot of readable but unexciting stuff which adds nothing much to either character or plot.
Also, Clark and Chavez are woefully underused, and when is the action supposed to take place? Apparently at least two years after Reagan and Bush (ie at least 1994), but with Russian troops in Berlin and the Soviet Union still intact (ie before December 1991). Twenty-first century hindsight doesn't do much for a book written in 1991 when the future was unclear. But the Israeli-Palestinian stuff, and terrorism in the US is more topical than ever.
So read this if you have a lot of time on your hands, and don't mind the slight tedium of the first half - the second part is well worth it, but if you want a good first Clancy and fantastic self-contained thriller then Red Storm Rising or the Bear and the Dragon are much more satisfying.