How accurate is the background removal?
Short answer
For the typical case — a person, product, pet or logo on a contrasting background — the cutout is clean in one pass, including hair strands and fur. The hardest cases are very low contrast (white on white), glass and smoke, and busy backgrounds, which can need a quick manual touch-up.
Accuracy depends more on the photo than on the model: even light, a plain wall and a sharp, uncompressed image give the model clear edges to work with. A forwarded, heavily compressed image or a subject that matches the background colour is where any tool struggles.
Check the result at 200% zoom on hair, fingers and glass before you use it. If an edge is wrong, re-shoot against a contrasting wall rather than trying to fix pixels — it is faster.