You have to see it in action to appreciate how cool this is. Get yourself a copy of Golly, load the pattern, and let it run for 34 million generations (which will take about half an hour on a modern machine). What you will see is a long diagonal line. If you zoom in to the upper left corner you will see the replicator itself. The rest of the pattern is an instruction tape that extends down and to the right. When it runs you will see the tape "running through" the replicator, which builds up a copy of itself piece by piece very, very slowly.

The cool bit is not that it replicates and destroys itself, but that it does so under the control of the instruction tape (which gets replicated along with the replicator itself). This allows you to fine-tune the behavior of the replicator. For example, you can change the rate at which it replicates by adding no-op instructions to the tape. This kind of fine-grain control over the behavior of a Life replicator has never been achieved before.