I like the concept but dislike the implementation.
I'm honestly baffled by the way emotions are handled. There are so many things you can do to artificially put your sim in any (positive) mood you want and they just keep adding more with every pack. You can use lamps, incense, aromatherapy, showers, ice cream, bath soaks, etc. to make your sim feel any way you want and I'm just like...why? Why do I care that my sim is energized right now? Why do I care that they're inspired? You could argue that those emotions help them build skills but skill building is only a small part of the Sims experience for me, and being able to do it slightly faster is not much of a draw. I do like that the flirty emotion gives them more success with romance because I feel that's a more interesting and realistic result. I know skill building and crafting are important to a lot of people, but to me having more complex and realistic ways for the sims to act is the most important part of the game.
Emotions should not be a means to an end (that I can't seem to figure out), they should be the RESULT of an event that has happened in a sim's life. I want my sims to be in certain emotions because of interesting gameplay events, not furniture.
Other people have made really good points about how positive emotions stack too much (I hate the decor one), and I think this is a big part of it too. One example for me is the Mom in my main family has done the Master Chef aspiration so her meals always give the family +3 happiness buffs. That's the same level of happiness that marriage or a new baby brings, and it kind of cheapens those events that my sims are equally happy from eating her tuna casserole. I want my sims to be "fine" more often and happiness to be something I have to work for, so that I can actually be excited for my sims when something good happens to them. I would be OK with all the less significant happiness buffs going away and only big life events like First Kiss or Promotion causing it.