Not very it seems
Theres an interesting paper which I linked to here . The paper looks, over the 2002-11 period, at the accuracy of equity analysts target prices. Irish analysts are included.
Among other things it shows on a country by country basis the accuracy.
Heres the chart. The data are TPMET for those interested. I It measures if the target price was hit at any stage in the following 12 months. So 0.5 would be that 50% of price forecasts , up or down , were hit at any stage in the next year.
Higher values indicate lower accuracy. Oops.