Hi-
Basically Feed forward compensation is to get higher gain without compromising on bandwidth (on the contrary to Miller). Or another way to think about it is feed forward (aka fast path) is a kind of low phase which decides stability and low frequency path (main path with 2 or 3 stages) is for high dc gain. Since there two path there will be an low frequency pole zero doublet relative to UGB, which may cause some under-estimation to settling related to UGB. This is the reason why people use this amp for the smooth signals like narrowband signals in filters rather step like i/p. Another problem is FF compensation is conditionally stable, hence we cant use this for any feed back network as this is the case for miller, this could be a problem for general purpose opamp.

Best regards,
Raj.