Is it OK to complain to God?

Maybe it is.

I noticed in Habakkuk 2:1, Habakkuk says he will stand on the watchtower, to see how God will answer his complaint. Most English translations say "complaint" here, although a few (NASB and King James) say "what I shall answer when I am reproved."
There are several mentions of complaint poured out to God n the Psalms, Psalm 55:2, 64:1, 102 (in the title, before verse 1), 142:2.

But weren't the Israelites punished for complaining to God in the wilderness? Numbers 14:2 says the whole community "grumbled against Moses and Aaron," and in 14:27-30 God says he has heard their grumbling and they will all die in the desert, none of them (except Caleb and Joshua) will enter the promised land. The King James says they "murmured against Moses and Aaron," and my Logos word search says this Hebrew word means "murmuring," and the lexicon defines it as "a complaint uttered in a low and indistinct tone."

So what is the difference? Here's my theory. When you grumble or murmur, you are mostly talkng to yourself, or to your close friends. The Israelites were saying to themselves "this won't end well. We are doomed!"
Habakkuk and the Psalmist don't murmur to themselves, they bring their complaints to God. They maintain relationship with God, while the Israelites were giving up on God.

So presenting complaints to God because you're staying in relationship, admitting what you are feeling to God, is OK. Grumbling or murmuring to yourself out of the attitude that this relationship with God has obviously not worked, and you are getting out as soon as you can, is a lack of faith.

So present your complaints to God. I think God appreciates our honesty. David and Jesus prayed "why have you forsaken me," do we really think we can be more spiritual than they were?

But I don't think we should just complain to God. We're also supposed to thank him, worship him and confess our sins.