I believe the true issue is misuse and abuse of resources. Many countries have an abundance of natural resources needed for survival but they are distributed disproportionately among the wealthy and political groups.
Of course overpopulation is a problem. Humans are living longer and longer. Our population is exploding all around the world. In the future, we will not be able to sustain our population. There will not be enough ground to live on and grow food on. Technology will certainly push this point further and further into the future. It is impossible to predict at what point we will no longer be able to live on this planet because technology is constantly offering new solutions. Eventually, our numbers will exceed the viable space on this planet. Rapid overpopulation does not allow technology to keep up. If the population grows faster than technology does, we will not have solutions to many problems like adequate food supply. It is important to be searching for future solutions now so they will be ready when we need them.
I agree that overpopulation is a problem. Of course, it may be that technological advances will allow us to solve some of the specific problems created by overpopulation, but I really do wonder whether the earth can support a population much larger than the one already here. Admittedly, doomsday scenarios from the 1970s predicted that overpopulation would lead to a fundamental collapse by now, so predicting the future is always a difficult task.
One problem that concerns me is just how we are going to deal with the overflow of garbage that humans create.
I think overpopulation is definitely a problem. As the above posters mention, the issue is not actual space for the amount of humans in the world, but the lack of resources. Already we are seeing the depletion of important resources, and too few people make it a priority to do something about it. In addition to protecting resources, I think it's important to educate people in poorer areas about contraception so that they don't have as many unplanned children born into poverty and increasing the population in the already too-crowded areas.
I have to agree that overpopulation is a problem in some areas, where in others it is not. Outside of that, one could only determine overpopulation upon the drain of resources in the specific area. If resources are not being depleted, on could argue that an area is not overpopulated.
At this particular moment in the history of Earth, there are some areas of the world that are overpopulated and some areas that could successfully support increased human settlement - the population is not evenly spread over the entire globe! Unfortunately, the population is increasing most rapidly in many of the areas that are least able to cope with more people. Ultimately, of course, the use of resources by those who have them available is depriving those who need support the most. Better methods of distributing resources would help, but the bottom line needs to be reduced demand.
I think that there is overpopulation globally, even though the population will decrease in some parts of the world. The problem is that the places where population is growing are also the poorest, and they cannot handle the people they already have.
For the next 25 to 50 years, population and its attendant problems will continue to be an issue. In the long term, however, it will not. Every country that has industrialized, since Great Britain did in the late 1700's / early 1800's, has seen their population go down, presumably as the economy transitions from agriculture to industry. China and India, with about 55% of the population of the world, are now industrializing; their population growth will slow and recede, if it hasn't started already.
I think overpopulation is not but overuse of resources is. The two are, of course, related. The real problem as the population grows is that we use more and more resources. Some of that resource use can cause real problems like global warming. If we can come up with ways of using less energy and less of other resources, the level of population would not be such a great issue.