Cathedral is both an attractive and interesting abstract game for 2, but...
The problem: it's broken. There is a first move that no setup with the cathedral piece or opponent's first move can block; even with very good play by the second player, the first player will still win by 2-4 points. Yawn.
I'm not going to detail the exact move, as I don't want to spoil the game for those who haven't found it yet. But, I will describe the principle underlying it: this first move essentially sets up a series of forking moves that either gives the first player lots of territory, or gives the first player some territory, while scattering the second player's pieces. This move can always be constructed, no matter how the neutral cathedral piece is initially placed, and the second player will be unable to recover from either resulting position.
The fix (Tom Lehmann and Don Woods): instead of placing the neutral cathedral piece before the first player's turn, place it after (along with the second player's first piece). Continue play normally.
Doing this allows the second player to effectively block both "prongs" of the initial forking move (with the neutral cathedral piece and his or her first piece).