I would say 90% of the radical left (certainly this side of the pond) are extremely dissapointed with the choice. They'd have preferred Warren.
On the 2nd point, and my understanding of American politics is not as good as Englands, but Trump looks to have a long way back to me. He's not down and out, but a long way back.
A big bit seems to be, that the Republicans and none aligned voters don't hate Biden anywhere near as much as none allligned voters hated Trump, and ultimately hated Clinton and Obama. If I were to hazard a guess, I suspect it will be difficult for Trump to whip up the same level of anger, possible against a woman or black guy, to a white, 70 something, fairly centrist bloke. There may be some dislike, but I doubt the same level of hate.
Biden for his part is playing a pretty smart game. Do very little, appear bland, and hope Trump makes enough mistakes.