The mouseover reduces "In my opinion" to Laŭ. Is this an error or a really cool feature of Esperanto that the "mi" is implied
It's an error. I've never seen or heard laŭ alone, and I can't imagine its meaning. ("Laŭe" (accordingly/alongly) is the closest, but would hardly replace "laŭ mi".)
I saw this comment, so I tried to answer without MI - "Laŭ, la vintro estos...". It's not accepted, so I guess Laŭ must have a pronoun.