"whatever the reaction" is correct and usable in written English.
You can use it to emphasize that you are prepared for any response, either negative or positive. For example: "Whatever the reaction, I'm determined to follow my dream."
Whatever the reaction the book seems certain to sell well.
Whatever the reaction they draw, the organizers say they are making headway, both emotionally and physically.
Whatever the reaction, the fact is that our disciplines are ever changing, regardless of the calendar and its cosmic inspirations.
Whatever the reaction, "Hopscotch" triumphantly escapes the genteel, fenced-off zone where opera is supposed to reside.
Whatever the reaction of parents to this information, their chances of doing anything effective about it have steadily diminished.
Whatever the reaction is to their new work, it is unlikely that the band will be too affected by it.
Whatever the reactions to the speech, Obama's general likability has improved across a variety of constituencies, including a wavering base and the political middle.
Whatever the case, reaction was immediate and severe, particularly when Mr. Brown said the following day — inaccurately — that "we are freezing the assets of Icelandic companies in the U.K. where we can".
Whatever the public reaction to Raury's statement when the broadcast is aired Tuesday night, the audience at the Ed Sullivan Theater was unambiguous in its support.
He did, however, subsequently reveal that his own mother told him she had always liked his opinions when he was on the New Jersey court, but wondered now that he was on the Supreme Court, "Why can't you do it the same way?" His answer: "We have to discharge our responsibility to enforce the rights in favor of minorities, whatever the majority reaction may be". .
All of which suggests higher oil prices to come, whatever the market's reaction to OPEC's latest pronouncements.
