Sounds good to me! Semantic layers help expose a more user-friendly view of the data, so it is easier to ask business questions and get accurate results. More technically, it brings modularity and reusability to SQL. Things like joins, aggregate functions, and dimensional expressions are encapsulated as new fields/objects. Typically this logic is rendered at query time rather than pre-computed and materialized. The advantage of that is more flexible iteration and composability. In essence they are highly glorified SQL templating engines.