The obvious benefit is that compressed data takes up less space on disk. Since you probably keep multiple copies of your database (multiple environments, DR, backups, etc), this space savings can really add up. High-performance enterprise-class storage is expensive. Compressing your data to reduce footprint can have a very real benefit to your budget. I once worked on an SAP ERP database that was 12TB uncompressed, and was reduced to just under 4TB after we implemented compression.
My experience with compression is that the benefit vastly outweighs the cost. Do your own testing, of course.