Technically, there's no such thing as a "bisexual" experience. A person may be "bisexual" in terms of describing their basic sexuality, but even then, I personally feel that the term is too abstract. That's just my personal semantics.
My first sexual experience with another woman was amazing. I had been in love with her for almost a year and over that time the chemistry just kept building. The sexual tension was driving us both crazy. There really was no reason why we both waited so long, but looking back I wouldn't have done it any other way. We are still together (this was many years ago).