Chapter 5 ends with Moses asking why the Lord did evil to His people. The Lord didn't do evil first off, Pharaoh did. Secondly, the Lord warned Moses that there would be resistance before Pharaoh would let them go.
How often do we want to just skip all the work and hard stuff to get to the good? It's during the process that the change happens and our character and faith grows. A seed doesn't instantly produce fruit. It has to go thru the process of growing first. No matter how painful it can be at times.
Chapter 6 I feel like God is trying to remind Moses that it is Him (God) that will actually be the one doing everything and they need to trust Him as Lord. I say this because of all the first person statements such as I will bring you out...I will deliver you...and I will redeem you.
Chapter 6 verse 9 says "but they did not listen to Moses, because of their broken spirit." Sometimes in our brokenness it's hard to hear positive and believe it will get better. God is so awesome though and doesn't leave or forsake us in our brokenness. Instead He stays with us and continues His plan of restoring and redeeming what was broken. He turns everything bad to work for His goodness!