The Rambam in yesode hatorah says that God has no emotions.
He does not change, he does not get angry nor have joy. Everything you see in tanach is just so that we can understand.
The commentary there says: "he does not get angry if you transgress nor get joy from your doing His will".
If so, why does he care about our service? Is it all for us only?
Kabbalists make a distinction (which may or may not be attractive to different people) between the אין סוף, the Infinite one that is completely beyond us, and the emanated פרצופים 'faces' of God. Our actions could never have an effect on the אין סוף, the Infinite one, but he has willed that they have an effect on emanations which are, at the same time, of Him, and just a garment of Him:
כהדין קמצא, דלבושיה מיניה וביה
"...like the snail, whose garment [shell] is of him and part of him..."
(cf., for example, ערוגת הבשם on Song of Songs, intro, 'klalim me-kitvei ha-ari, first paragraph)
(This is certainly not the religious path of the Rambam though.)
What does it mean to serve Hashem?
If Hashem is perfect why do we need to serve him, when you serve someone something it is generally because they do not have it otherwise it would be pointless to give it to them. Unless they have no control over them self and any desire they have they wish to do.
So we must say Hashem NEEDS my mitzvos and i dont think there is anything wrong with saying hashemneeds something. The need we mean by hashem is not like we need to eat etc. Its more like i need purpose, the fact that i neeed purpose does that make me weaker no it makes me more human.
So too hashem what makes hashem more hashem is that he needs mitzvos.
IT's not true that God not have emotions, It's misinterpretation of "God don't feel happiness or sadness". Actually One of God's Quality is eternal bliss. And he never loses it. He remains in Eternal content . Our actions are inspired from instantaneous motives and have temporary results .Hence he keeps himself remote from our actions although in some form or other he encourages us to do the right thing ,but it's our choice whether to follow his call or not.
