Worth separating two things people conflate: this is an excellent reference and a mediocre first textbook.
As a reference it is close to unbeatable. When I need the exact statement of the master theorem, or want to check an edge case in the analysis of a heap operation, this is the fastest place to find it and the statement will be correct.
As a way to learn algorithms it is too complete. Every case is covered, which means nothing is emphasized, and a first reader cannot tell which of the twelve pages on a topic contain the idea and which contain the bookkeeping.