So, when it's time to frame a photo with your DSLR camera, you'll need to decide on the viewfinder vs. LCD debate.
Despite the obvious qualities of the LCD screen, pro photographers (myself included) will still use the viewfinder over the screen. And here are the reasons why.
Steady hands. Holding the camera out at arm's length while looking at the LCD screen -- and then keeping the camera steady while trying to zoom in on a subject -- takes a lot of effort. By using the LCD screen in this way, you'll often end up with a blurry image. Digital SLRs aren't the lightest of beasts, and it's far easier to produce a crisp, sharp image when you're holding the camera up to your eye to use the viewfinder. That way you can support and steady the camera and lens with your hands.
Bright light. This has to be the biggest problem with LCD screens -- depending on the quality of the screen, you likely can't use them in bright sunshine because of problems with glare. All you'll be able to see is reflections off of the screen. In addition, the crystals contained within LCD screens have a tendency to "flare" in bright sunlight, making the situation worse.
Batteries. Using the LCD screen to compose your shots drains the batteries in your camera much more quickly than using the viewfinder. If you're out shooting, with no access to power points to recharge your batteries, you'll be grateful for the extra battery power!
The human eye. At the end of the day, as clever as digital cameras are, the human eye is able to resolve more detail than an LCD screen. So you'll end up with a sharper and more precise view of your image by using the viewfinder.
Reviewing images. No matter how good your LCD screen is, it's unlikely to give you a completely accurate overview of the image you've just taken. Most LCD screens tend to overexpose an image by as much as one full stop. It's best to acquire the technical knowledge about photography to give you the confidence that your settings are correct and your images are properly exposed, rather than relying on the LCD screen to determine image quality.