"I would like you to do a favor though.." - right when the congress approved aid was blocked seems damning. Context is everything.
I think it really depends on how it was said in the call, it's difficult to say for sure if he was just going off a bullet point list of concerns with Ukraine, or had his mind set all that time on attacking Biden.
I guess we'll never know for sure, wouldn't be at all surprised if that was the intention though.
Edit: Also about the aid approval. I think the approval happened shortly after the call became public, not after some action was made against Biden's son, so it may be a case of "dammed if you do, damned if you don't".
The call itself is not damning, but there's clear evidence that Trump tried to hold up military support.
Now, how illegal or immoral that is, is a separate question entirely as well.