Was Immediately Taken Aback?

: to surprise or shock (someone) —usually used as (be) taken aback When I told him my answer, he seemed taken aback.

Is taken back correct?

Taken back is a corruption of taken aback, a long-standing idiom meaning "taken by surprise." Taken back properly means "to be returned." These days, however, taken back is used in statements like, "I was taken back by his rudeness." The snarky online Urban Dictionary cautions that taken back is a "phrase used by semi- ...

Is taken aback negative?

Of the two, "taken aback" is stronger, in my opinion. It's also exclusively a negative reaction, as far as I know. "I was surprised by my friends at the airport" is a positive experience. You couldn't substitute "I was taken aback by my friends at the airport" and have the same positive tone to it.