I've now played qfg4.5 twice as fighter and twice as thief, each one on both xp 32 bit, and win 7 64 bit. Thoroughly enjoyed it, but not as much as QFI. In QFG 4.5, a lot was taken from King's quest V, the snowy mountain area, the sea voyage to the island, and a bit of space quest music thrown in.
Getting back to QFI, I found it rather easy, especially the BT part, but quickly lost interest in that. It was too tedious, yet doable. Too much hit and miss, but Blackthorne says the BT part will be more lenient in the update. There is so much more that can be done, things like the hanging plant on the edge of the stables, the well by Rayford's house, etc.