But I paused long enough to ponder whether the question refers to my business, or to the-world-in-general.
If the latter, then for sure, Internet marketing is here, it works. Look at what you have spent in terms of time and money over the past year buying products and services over the internet, reading online newspapers, searching written papers for information and so on.
But the model that works for you (selling downloadable software) has to be different from her model (selling accessories by mail order) and the model that works for me (have brain, will train).
In once case it is eminently possible to set up a web site, have the money sent via PayPal to your credit card account, and spend the rest of your life at Eddy's bar on Grand Cayman knowing that the web hosting service will take the annual payment automatically.
In another case you'd need a shipping-and-handling staff to stay behind.
In my case, it's really all about standing in front of people.
So the question boils down to how much time and money you need to put into your web site and email marketing campaign to get the money your business deserves.
The Montreal Deli does very well solely by word-of-mouth and its regular customers.