THE message and THE audience. It's very easy in the building of your site to get those two lost in the details. Planning is a great help, particularly if you have lots to say. What may be plain to you can be confusing or even misunderstood by first time visitors. Many times I have visited a site and the graphics were great and there was the latest in technological wizardry, but it was hard to tell just what the site was about.
Communication is what counts.
Let's look at the three types of info sites. This offers a lot, but can be confusing to new visitors. Great for first impression but can be a turn off to folks that are in a hurry to find something out. All three can and have been effective. They have their places.