One other flaw I just put to wtbob below is that the way the document structures elections, the result is a two-party system that simply cannot adequately represent hundreds of millions of people of diverse backgrounds. Given that the document was raised explicitly in response to inadequate representation, that's a problem. Is it the worst problem ever in a constitution? No, but it is still an issue.

Edit: For comparison, here in Australia we have a couple of major parties, a couple of big minor parties, and a scattering of small parties all in government at the moment. Or in Germany, it's entirely normal for major parties to have to band together to form a majority in order to govern - from memory, Merkel's party gets about 25% of the vote, and has to create a coalition with other parties to get the majority required. There is space in these systems for new parties to rise, and the concept of "you're either for us or against us" is nowhere near as prevalent as in the US. These systems have their issues too, but they are more representative of their people due to their flexibility.