Honestly, who is Allah?

He is Allah , other than whom there is no deity, Knower of the unseen and the witnessed. He is the Entirely Merciful, the Especially Merciful. (Qur'an 59:22)

He is Allah , other than whom there is no deity, the Sovereign, the Pure, the Perfection, the Bestower of Faith, the Overseer, the Exalted in Might, the Compeller, the Superior. Exalted is Allah above whatever they associate with Him. (Qur'an 59:23)

  

He is Allah , the Creator, the Inventor, the Fashioner; to Him belong the best names. Whatever is in the heavens and earth is exalting Him. And He is the Exalted in Might, the Wise. (Qur'an 59:24)

Uhh yeah.. but who is He? The "Muslim Moon God" or something?

Nope. Allah is the Arabic word for "The God" with no partners associated. Zero, nada, nil, zilch, zéro, null.. You get my point.

Al (The) + Ilah (God) = Allah (The God)

It's as simple as that! It does not mean "Moon God" or "The Muslim God" (Lol?). It means The One True God - Allah.

Since many people seem to be "confused" about whether Muslims worship Allah or "God", I thought I'd clear some doubts.

Allah is exactly the same word which the Jews, in Hebrew, use for God (Eloh - Sounds similar eh?), the word which Jesus Christ used in Aramaic when he prayed to God. And YES! Allah is the God worshiped by Jews, Christians, AND Muslims.

So, if we were to crack an Arabic Bible open, we'd see that the word Allah DOES exist in the Arabic Bible. Most Arabs, regardless of their religion (Christianity, Islam, or Judaism) call God, Allah.
 

However - It should be noted that God in Islam is One and Only. He, the Exalted,does not get tired, does not have a son (ie Jesus) or have associates, nor does He have human-like attributions as found in other faiths, because of the significance that the Oneness of God holds in Islam.

Additionally, the word "Allah" cannot be made plural or given gender (i.e. masculine or feminine), which goes hand-in-hand with the Islamic concept of God.

In the name of Allah, Most Gracious, Most Merciful

Say: He is Allah, the One and Only; 

Allah, the Eternal, Absolute;

He begetteth not, nor is He begotten;

And there is none like unto Him. 

 So there you go. That's all that "Allah" means.