One of the chief debates involved in the Genesis account is the age of the earth, based on the meaning of the Hebrew word yom. It could mean daytime, the hot hours of the day, an actual twenty-four hour day, an age, or an indefinite span of time.
According to Young Earth Creationism (YEC), the word yom in the days of creation is meant to be taken as standard, twenty-four hour days. There is good evidence for this, such as the use of the terms "evening" and "morning" (Hebrew `ereb and boqer, respectively) and the numbering of the days. These terms, YEC claims, would not make sense in the context of ages or periods. YEC also has the advantage of consistency: more than ninety percent of the uses of yom in the Bible refer to normal days.
Old Earth Creationism (OEC) holds that yom refers literally here to certain ages of the creation of the universe (thus, OEC is also called "Day-Age Theory"). Most of the OEC arguments are scientific as opposed to theological or Biblical (not that the arguments are unbiblical, but that they are not arguments based on Scriptural exegesis). Indeed, some of the science seems very realistic and plausible. The largest objection brought to OEC is the idea of animal death before the Fall, which YEC claims is contrary to Romans 5:12. However, OEC contends that Romans 5:12 applies only to humans both physically and spiritually, for, since we know animals did not receive sin or the law, there would be no reason to only apply one of the things mentioned to animals. The OEC camp also reminds us that plant death must have existed before the Fall, as well, since plant cells die when one picks fruit or even does minor tending tasks on the plants.
It is my opinion that the primary issues between YEC and OEC are scientific as opposed to theological. There are many honest, God-fearing men on both sides of the issue, and both sides still affirm the literal reality of the Genesis creation account. A far more pressing issue than the age of the earth is the teaching of evolution, which in fact does contain many theological and scientific issues.