After a day or two of getting acclimatized, he became CLEARLY "her" cat. Once in a while, he would let me scratch his head a little and once, I had him purring, but it was her that he went to. She is down in Oregon, ATM, looking after cuz's house and dog, and he and I took all of a day to finally bond. He can still be skittish, but he has definitely warmed to me.
He's a Russian Blue*Tuxedo cross, and smart as a whip. After 2 days, he'd figured out how to open latched doors, as long as he can push them - he's not yet determined how to open "pull" doors. All our doors have lever handles, so it wasn't THAT difficult for him, though. My son once had a cat that had figured out how to open doors with round handles.
Now, The New One (Max) is working on mastering the Venetian blinds.
She got him a perch that attaches to a sliding glass door with big suction cups, and he knew it was his before it was assembled. Spends lots of time in that, as well as on the floor beneath it, watching the next door cat launch itself at him, and crashing into the glass. He doesn't even flinch, which I'm sure drives her nuts.