What was new about the Holy Spirit at Pentecost?
At Pentecost, the new aspect was not the Spirit's identity as a person of the Godhead, but His coming down in a specific role to empower. This empowering role was something totally new, as Peter explained by quoting Joel's prophecy.
Les teaches that the Spirit being a person of the Godhead was nothing new. What was new was that He would come down in this kind of a role to empower. This was something totally new. Peter said this was that which was spoken by Joel. Joel had prophesied that God would pour out His Spirit upon all flesh, with sons and daughters prophesying, old men dreaming dreams, young men seeing visions, and servants and handmaids receiving the Spirit. Les stresses that all prophecy is directed to Israel, not the church.