It adds a lot of things that work in the background, in contrast to the horse ranch EP that adds a lot of "substantial" content and no overarching feature, to compare. Growing Together adds depth to family gameplay, interaction with other sims, milestones that you can unlock depending on the things your Sim actually achieve... This EP comes with a lot of things you might not see if you don't work for it.
But it also comes with more obvious gameplay, such as improved infants, activities, a new type of venue...
I personally don't use the community lot that much but I really like the pack overall for the depth it brings to the game.
I voted "not at full price" because the whole game is just too damn expensive with everything bought at full price and I feel like Sims 2 (and Sims 3 to an extent even though I didn't like the game) had way more content for the same price tag (one could argue that 40€ 15 years ago was worth more than 40€ now so TS4 packs are technically cheaper), but I do recommend it a lot :D