Subacromial decompression is generally effective in relieving symptoms associated with shoulder impingement syndrome, such as pain and restricted movement. The procedure aims to create more space in the subacromial space by removing or trimming structures like bone spurs or inflamed bursa. While success rates vary, many patients experience significant improvement in shoulder function and pain reduction. However, individual outcomes can differ, and the effectiveness of the procedure depends on various factors, including the specific condition and patient characteristics.