Recipe as written above is lacking. Swap the measures of amaretto and grapefruit and it might be at its ideal (up). 4:2:1 tequila-amaretto-grapefruit is worse somehow... All these shakes were strained up. Interesting flavor combo that needs surgical ratios and inspired glass presentation (up? rocks? rims?)... Can you take this higher?
Very interesting drink. Initially like a margarita, but then you get the bitterness of the grapefruit and amaretto. Very refreshing, but hard to describe.