It is worth trying to put into perspective the difference in picture quality those larger sized pixels will produce. One way to think about is that a Digital SLR will produce ultimate quality, while a Compact System Camera will produce excellent quality. If all you are planning to do is make some A4 size prints as a maximum size, a Compact System Camera can do that with perfectly good quality. It is only if you are a professional or someone who demands the very best that you will feel a Digital SLR is the only choice for you.
How important the quality levels are to you, only you can decide.
At the end of the day what you do with the camera is far more important than the size of the pixels it has.
Sensor size will also affect the look of your pictures and the view your lens will give. Some professional models have what is known as a "full frame" sensor, meaning it is the same size as an individual frame of 35mm film and the pictures it captures will be framed exactly the same as on a film camera. Most digital cameras have much smaller sensors, which helps to keep costs down.
However, a smaller sensor will not 'see' the whole of the image produced by the camera's lens, so comparing the view you get with a smaller sensor to that from a full frame sensor it gives the appearance that you have 'zoomed in' or cropped the picture.
This can be a limitation to your picture-taking. For example, when shooting landscapes you want the camera to give a wide angle of view so that you can fit a lot of the scene into your picture, but when used on a camera with a smaller sensor a wide-angle lens will not be able to 'see' as wide a view as it would on a camera with a bigger sensor. On the other hand, when using a telephoto lens to zoom in and magnify subjects that are further away, a smaller sensor gives an advantage, as it makes the subject look bigger than it would when used on a camera with a bigger sensor.
Digital SLR Basics
Digital SLRs and Digital Cameras Key Differences
Digital SLR or Compact System Cameras
Digital SLR Handling
Help for Beginners
Lenses and Accessories
Buying a Camera Lens
Digital SLR Accessories
Learn More About Features
Resolution and Sensor Size
Manual Exposure Modes
Help With Tricky Lighting
Live View and Articulated Screens
Depth of Field Preview Button
Current and Recommended Models
Summary of Current Models
Recommended Digital SLRs
Digital SLR Guide Author
This guide was written by Ian Younger
Another issue with smaller sensors is that your pictures require a greater amount of enlargement when printing. If your original image is much smaller, because of the smaller sensor, it will need to be enlarged more than the image from a larger sensor would in order to make it the size you need for your print. If you only want to make a 6" x 4" print to pop in your album this may not be too much of a problem and the difference won't be noticeable but if you want an A4 sized print or maybe something big enough to frame and display on your wall then the extra enlargement needed from the smaller sensor will make the difference in quality more obvious.
Professional DSLRs generally have the biggest sensors, while entry-level models often use the smaller APS-C sized sensor. Both Canon and Nikon use this size, although the two makers' sensors are fractionally different in size. Olympus use a smaller sensor, known as 'four-thirds' and sensors in compact cameras are smaller still. A number of CSCs, such as those from Sony and Samsung also use APS-C sensors, whilst those from Panasonic and Olympus use the four-thirds size.