They can be both good and bad.
It's good to expect things from God because it shows that you believe Him ... you trust Him. Expecting good things is healthy! It's positive and optimistic!
But, there are also expectations that can be bad. It's the kind of expectations that other people may have of you. These are the hardest to fulfill. These expectations can be unattainable, unrealistic, and just plain ridiculous.
Expectations can also lead to quite a bit of disappointment. Bummer for both sides. The expertor & the expectee (yeah, those aren't real words, but you get my point). Both sides can be equally disappointed.
But, to be a Christ-follower and to live for Him means we are not disappointments. He loves us just the way we are. He created us and knows every bit of our make-up. He designed us. He has plans just for us.
It's important to put our hope and trust in God to meet our expectations and not people. People will fail us every time. We're all human.
And, it's equally important to recognize when we've disappointed someone ourselves, no matter whether it be intentional or not. At that point, the only thing to do is share your heart with that person & pray that true intentions are seen & understood.
No matter how many times we are misunderstood (and believe me, for some of us it's more than we'd like), it's comforting to know that God sees. He knows our every motive and intention. He sees our heart & sometimes He's the only One that can comfort us.
“O Lord, you have searched me and you know me. You know when I sit and when I rise; You perceive my thoughts from afar. You discern my going out and my lying down; You are familiar with all my ways. Before a word is on my tongue you know it completely, O Lord.” (Psalm 139:1-4)
Sometimes ... actually ... all the time ... He knows us even better than we know ourselves. Wow. Whew. How that takes the pressure off of us to try and understand a lot of why we do things. We don't have to always figure it out. He knows.