I think yoga is the real highlight -- there seem to be varying degrees of expertise for each pose, and quite a few poses. Yoga class is a hoot, so send your sim at least once, even if it costs $110. The Ashram, the new gym, and the Perfect Balance spa all offer classes; I haven't placed the massage venue yet, so don't know about that. Your sim will change into an athletic outfit and then get rid of the shoes.
The Brain Boosting yoga routine gives a +1 Inspired moodlet for 8 hours; the Concentrated Mind gives +1 Focused for 8 hours. I haven't tried the Energy routine yet; my guess is it gives a +1 Energized moodlet. So if your sim is in a job that needs those emotions, do the yoga routine (I think it takes an hour) beforehand.
Incense comes in 6 different fragrances: Lemon (inspired), Sage and Patchouli (happy). I guess Invigorating Cinnamon will give an energized moodlet and Sharpening Saffron a focused one. There's a Romantic something that almost certainly gives a flirty moodlet. Each costs $20; your sim has to inhale the aroma, and unlike incense in TS3, it will go out after a while. You can find incense in the lighting category.
I haven't listened to the New Age station yet, but there's new music for the loading screens that is very pretty.
I'm really happy that my sim can put her yoga mat and meditation stool in personal inventory to use anywhere. There are yoga instructor mats, too, but I don't know if you can place one in the park and have an instructor show up.
Hairstyles and clothes are nice. I like the long robes the best. The new wall patterns are very pretty.
I was afraid this pack might be lighter in content than Outdoor Retreat, but they did so much with yoga animations that it's really impressive. I was expecting a pratfall or two, in addition to good poses, but there are wobbles, awkward angles, partial stretches, etc.
Oh, and even if you've already made up your mind, watch the trailer. It's really cute, in a mellow sort of way.