Should Lincoln's position in handling the secession crisis be judged favorably or unfavorably?

I would argue that you have to judge Lincoln's position
favorably.  I do not think that Lincoln could have done any better than he
did.

When Lincoln was elected, the South already distrusted him
completely.  Even so, Lincoln tried to allay their suspicions.  He gave a number of conciliatory
statements, saying, for example, that he would not try to end slavery in the South.  There is not
much more that he could have done in that regard.

The other choice
he had to make was whether to just let the South secede.  You can say he should have just let
them go rather than having a way, but that is unrealistic.  I cannot imagine any president
thinking that it would be a good idea to just let half of the country leave and become a
potentially hostile power right next door to the United States.