The phrase "it has to be said" is used to introduce a statement or observation that the speaker believes is important, true, or noteworthy, especially when it might be unexpected or contrary to what has been discussed previously. It's a way of emphasizing the significance of what is about to be said. In the example you provided, "The result, it has to be said, is genuinely exciting," the speaker is emphasizing that the result is indeed exciting and wants to make sure that this observation is acknowledged or recognized by the listener.

"has to be said" = "must be said"

It's common to begin a remark or opinion with the phrase "it has to be said" when the speaker feels strongly about it. It serves as a manner of highlighting the importance of the next statement, which should be acknowledged or appreciated. The speaker emphasizes that they believe the result to be actually interesting and notable in your example phrase, "The result, it has to be said, is genuinely exciting." It serves to support their claim and ensure that the listener comprehends the speaker's viewpoint on the thrill of the outcome.