crossing often (always ?) come too late. The momentum is used to anticipate the moment where the 2 will cross, offering a signal to take into account.
Does not work well in a range market. Signal comes too late and is thus in opposition with the market timing.
Seeing such a trap is trivial as you won't buy if the market is slightly bear or flat.
Signals is quite good to detect the begining of a bull/bear market.
Can display some interesting divergence.
This indicator has a better usage if you use it on several time interval of the same market.