First off, don't listen to anyone who says BOC sucked after the first three. This is the typical nonsense that most people do with all bands, and it's generally not true.
Most bands tend to be at their best during their mid period, because they still have the energy, but have honed their skills. During the later period they seem to get burned out, or change their direction too much. They still get great songs out of it though.
I'm not trying to discount their first three. There are great songs on those albums, such as Wings Wetted Down, Astronomy, Cities on Flame, and Flaming Telepat