Patching concrete is not always very difficult, as there are patching compounds you can buy at most hardware stores and which mix up in a simple bucket, without having to get out a wheelbarrow and shovel and mix up a huge batch of actual concrete. However, this doesn't mean that you should always patch up concrete driveways, as there are times when certain damage may signal that you need a new driveway altogether. Note when that is so you know when to call for concrete services rather than relying on a simple patch job.
When the concrete has separated in certain sections
A crack in the concrete can be repaired only if it hasn't gone all the way through the concrete. If there are sections of concrete that have separated or broken away, these won't be held together by simple patching compound. You might add the compound and the two sections will adhere for a time, but once you drive over it or it goes through another freeze and thaw cycle, it's like to simply come apart again. In these cases, you probably need to have the driveway pulled up and replaced, or at least have one of those sections removed and replaced with fresh concrete that will attach to the other section.
When one section of concrete is heaving
Heaving means that a section of concrete has lowered itself below the rest of the concrete. It may have only cracked slightly in this case and has not yet broken in two, but this typically means the ground under the concrete is not strong enough to support that section. Rather than trying to patch any crack that has formed, it's good to call a concreter who can pull up your entire driveway and treat the soil under it with lime, clay, or another material that will make it strong. A new driveway can then be poured that's level and even and won't suffer further damage.
When the top layer has lots of spalling
Spalling refers to slight cracking of the top layer of concrete; this may resemble spider webs all along the surface. This often happens because concrete has gone through many freeze-thaw cycles and has expanded and contracted, allowing the top layer to suffer these surface cracks. This is typically a sign that the concrete has become weakened. It's not usually good to try to cover spalling with patching compound as this won't keep the concrete strong. A new concrete driveway may be a better choice for avoiding inevitable cracks when you see this spalling.