They were preceded by a generation of single-core Android 2.x tablets, which were terrible. And that includes the original Galaxy Tab that was sufficiently Google-supported to get access to all the proprietary Google apps and the Marketplace.
The best devices of the Honeycomb generation are pretty compelling, especially after getting an upgrade to ICS.
The only Google sanctioned "tablet" from that time was as you mention the Galaxy Tab. The only reason it had the market was because it was essentially a big phone. In Europe, you even pop a sim in it and make calls out of the box. However, the others were not sanctioned thus hardly qualifying as a "generation" and even the Galaxy Tab was discouraged by various people involved in Android development.
The best devices of the Honeycomb generation are pretty compelling, especially after getting an upgrade to ICS.