Oh yes! It would be fabulous for after-schooling. Mine is first grade (according to birthdate) and also loves words. He has been delighted by it. There is lots of rich depth within the clear and simple explanations of all the types of words.

We only do about 15 min or so each day and just read together and talk about it. We have started with the Grammar book as they recommend. According to Publisher recommendations: After section one of Grammar Island is done then you begin to add the Vocabulary book (Building Language), Practice Island starts at the end of Grammar Island. You start Sentence Island once four-level analysis is strong as seen in the practice sentences. (Chart is a little unclear here but shows begin Mud Trilogy (literature component) after you get going in Sentence Island.) Poetry (Music of the Hemispheres) begins after you complete Practice Island.

They break it down into 4 parts like this:
1. Grammar Island
2. Building Language
3. Practice Island and Sentence Island
4. Mud Trilogy and Music of the Hemispheres

The characters in the books are introduced in the preceding curriculum pieces. We first see Mud (the fish) in little glimpses in the Grammar book's first few pages. When my son first noticed him and pointed him out, I was able to say "That's Mud, you will get to read his adventures later in our studies."

In Sentence Island we get formally introduced to Mud and friends as he tries to figure out about sentences.

The Grammar is not dry. It's very imaginative so it's fun to start with it and begin pondering language. It artfully gets in to all the pieces of language and explores what those pieces tell us and how they work together. My son was familiar with Noun/Verb/Adverb/Adjective and he has not been bored. It has deepened his understanding and feels like a story. He laughs at the humor and enjoys the visuals.