MapInfo's got a great discussion list hosted by Directions -
http://www.mapinfo-l.com , they actually have good MapInfo vs. ArcView threads in there, search the list history.
More "serious" GIS often can't do many things MapPoint does very simply, it's really complementary technology in my view.. Also, Mapping Solutions has an add-on which puts MapPoint fairly seamlessly right into MapInfo and ArcView called Map-In-A-Box.
Eric