Fianchetto bishop vs. normal bishop? I have found the following disadvantages of the fianchetto bishop:

1) The diagonal it controls is often blocked by the knight in its natural square.

2) The diagonal it controls is often blocked by central pawns of the same team or of the opponents.

3) Advancing the knight pawn (b2 -b3 or g2 - g3) somewhat weakens the pawn structure.

4) If the other bishop is developed along its normal diagonal, for eg.to b5,then advancing the knight pawn - b2-b3 cuts off the escape route for the other bishop - after for eg. 4) B-b5 a6 5) B-a4 b5 and 6) B-b3 is not possible because of the pawn at b3 and the bishop is trapped. So it somewhat impedes the development of the other bishop.

5) The fianchetto bishop cannot be defended by a pawn and is vulnerable to attack from the sides. Also the 'hole' in the pawn structure can make the rook vulnerable if the fianchetto bishop is moved from its b2 or g2 spot.

For these reasons, I've personally never preferred the fianchetto.

Yet, despite these drawbacks, the fianchetto development is often used in certain openings such as the Sicilian dragon and variations of QGD. Some players even open the game with the fianchetto. 

So, overall, is fianchetto development a good idea and under which conditions is it justified? What are the points to keep in mind during fianchetto development?
All the things you say are true! But fianchettoed bishops have some advantages as well. Here are a few:


They control multiple central squares at once. A fianchettoed bishop attacks half of the center four squares (e.g., a bishop on g2 attacks e4 and d5). Bishops not on the long diagonals can't do this.
They also can attack multiple squares around the opponent's king at once. A Dragon bishop on g7 facing a queenside-castled king on b1 casts its eye on c3, b2, and a1.
They can attack and defend simultaneously. A bishop on g2 has a lot of influence over the center squares of e4 and d5, not to mention that it can also eye a black pawn at b7 or the rook behind it at a8. But it also protects a castled king, covering f3 and h3.
It's not easy to attack them. A bishop at b5, say, is often forced back to b3 with ...a6 ...b5. And Black often even attacks it again from there, say by ...Na5. On the other hand, a fianchettoed bishop on g2 is nicely tucked out of play. Usually the only thing you have to worry about much is an opposing bishop coming to h3 supported by a queen.


Deciding where to put your bishops involves a lot of tradeoffs, which include the positive aspects mentioned here as well as the negative ones in your question.