Do I think that Joe Biden will work within the law? Yes.
Do I think that he has shown he is willing to change his views as people from his party or others present them to him? Yes.
Do I know that Biden has a campaign finance reform plan? Yes:
https://joebiden.com/governmentreform/
Do I know that Biden has a term limits reform plan? No. He has said before that he believes in term limits for the president and not for congress, I think this is a mistake - his argument (circa 2019) was that there is value to gained knowledge, which I agree with, but there is also danger in concentration of power - so I hope that there are enough people that will work on this - but I do not believe that a Joe Biden administration will really take on this.
But, the real reason I think Biden is a good candidate - because there are always priorities in an administration that need to be solved and I believe he is a candidate I trust to prioritize these. At the moment - it is an efficient, coherent, science based solution to the pandemic and it's effects - I believe Biden will work hard to create this - something that Trump clearly is not capable of (and actually actively works against).
So, I am certain that a Biden administration will not solve everything, but I am certain it will prioritize the current crisis properly (which the other candidate does not) - and if he has time to deal with other stuff, at least one item for politics he seems to want to address (campaign reform).
I am not upset that Obama did not bring us closer to better health care, Obamacare is a very small start - but that administration had a financial crisis it had to concentrate on - and because it succeeded in that hard job - I believe too many people gloss over it and point that he did not do other stuff he talked about - he tried, but he prioritized properly, and I believe Biden will too.
Obama was a popular president despite the fact that a lot of the stuff he talked about was moved very slightly - people recognized that his administration took the hard choices and got America out of a very bad financial crisis - likewise, people do not like Trump because they recognize that he fumbles his (very big part) in handling this crisis.