There are several features of ALM I found to be extremely valuable.
This question should actually be divided up. Several companies receive a different value add from different components of ALM. Some use it only for managing tests and defects and leave out requirements.
But just for sake of overall added value to me, the Test Planning and Lab portions are extremely valuable especially pertaining to a BPT license. Creating your core BPT components and mapping corner and edge test cases from that makes it easy to create regression test beds as well as facilitate Agile development. Also, if you are talking automation, the BPT component is critical in helping with the BPT test driven framework. Of course, the Defect module along with the Test Runners are key for execution and defect reporting. I love the ability to customize different attributes to defects in order to facilitate a specific release type.