Camera comes in so many flavors. They have so many different functions and abilities now it's insane. Some of these functions may be more important to you then someone else. You may want to be able to look at your DSLR pictures on your iPhone and send them to friends before getting home. Some DLSRs can do that now. Some characteristics may seem important, like MegaPixels, in reality effect the final image a lot less then you'd imagine.
One characteristic that's often overlooked when comparing features is the sensor size. You've probably heard the terms "Full Frame", "APS-C", Crop Sensor, 1.6X, 1.5X, Micro Four Thirds, etc... These are all terms that relate to the sensor size in some way.
To me, because of the subjects I shoot, this is the most important part of my camera.
The good then about having a larger sensor is that:
-It's easier to get a zoomed out picture.
-The ISO can go up higher without causing as much noise. This means you can take pictures in lower light. This can be up to 4 stops less light. This can be the difference between getting the picture or not in certain low light environments.
-Final image has more in focus. This is a bit misleading and basically is due to not having to have the magnification of the crop sensor lens. Read about Circle of Confusion if you want to learn the truth behind this.
The bad thing about having a larger sensor:
-The larger the sensor the more the camera cost.
-It's harder to get a zoomed in picture (though you can crop in).