Matt has some issues with both Manifold itself and the quality of its online help (or lack there of; love the redirect to an IP address on the forums, quite professional).
The reason we bought Manifold was to have a GIS in which to create nice maps of our large datasets in an easy way and serve them out to the web. While there were plenty of warnings that Manifold’s website was full of hyperbole & BS, I choose not to heed them.
Matt concludes that open source GIS (uDig/QGIS/Mapserver/MapGuide) might be a better choice in the long run for most users looking to escape the ESRI stack. This probably regulates Manifold to an Opera like status among GIS users. A fanatical fan base, decent product, but an also ran in the marketplace.