This definitely increase the quality of my recordings (I use an Olympus brand voice recorder). I record class lectures on the lowest quality setting and they come out great.
Sometimes ill spend 5 minutes removing background noise with audacity (very easy, just look up a tutorial on Google) and the result is amazing.The microphone is directional so you want to aim it at the thing you are recording, but it tilts up and down so you can leave the recorder flat on a desk and aim the mic towards the speakers mouth.
Remember, Olympus voice recorders have a microphone sensitivity setting. Use "dictation" if you are going to be recording yourself or someone right in front of you (within a few feet of the microphone) and use "conference" to increase the sensitivity to record things like a lecture where the speaker is more than a few feet away. Audacity can be used to remove background noise and make the voice clearer, and also eliminate the noise of yourself or someone else typing notes if that's a problem in your recording.
I've also used this on my mac book to video conference and my voice was MUCH clearer than using the tiny built in microphone. It works great buy you need a cheap USB audio adapter because the mac book audio port doesn't work correctly with this microphone
For the price, this is worth every penny. Unless you have a really high quality expensive voice recorder, this microphone is going to be better than the one built in.