Adwords is also a great testing ground for your marketing system. Within one or two days, you can tell whether your marketing system is working or not by tracking your conversion and sales rates. You can tweak your headline and colors to see which is more effective by running it through Adwords for instant results.
However, it takes some time to master Adwords. If you are a beginner, I suggest setting a low daily budget. Adwords has a steep learning curve, and if you are not careful, you can lose a lot of money. Buy up on the top Adwords guides on the market, and read them. Take notes along the way, and apply the tips in your campaigns. You do not want to take any chances when you are spending money for every click that is made.
Weigh Adwords against your other advertising methods in your promotional campaign and see how it fits in. I do suggest any online marketer use Adwords in some way, but the degree that you use it will depend on your experience and your results with it. Some niches have a lot of competition in Adwords and hence it may not be suitable.