Around my fourth song I started noticing the effect that pitch bending (or 'portamento') can have on a musical score. It gives the musician a complete new array of possibilities by blending notes together. Guitar songs using pitch bend can give a song an overall feel of smoothness, when used properly. See if you can spot the difference in the examples to the right (press play button).
The top version sounds quite boring. All notes play note by note without any interaction with eachother. When you play the bottom version, the riff gets more vibrant. This is because the notes seem weaved into eachother. This effect can be done using the pitch bend wheel on your MIDI keyboard. If you do not have an actual MIDI keyboard, then don't worry. You can also add this effect by hand in Reason.
Select your guitar instrument in the sequencer window. The sequencer window is the one where you place all your notes. Then right-click on the instrument. In the popup window that now appears, click 'parameter automation'. Tick the box that says 'pitch bend' and press ok.
Your instrument should now have an extra bar beneath is, where you can manualy add pitch bend nodes. One tip on the pitch bend effect is, to not overdo it. If you use it too often throughout a song, the impact of it will wear off and you'll probably won't reach the desired effect.
More on pitch bending