My first product was the red basic set (mentioned above) but I have very vivid memories of getting the 1e PHB for xmas.
I was at my grandma's and I spent the first night creating characters.
It was so cool, after playing Basic D&D for a while, to actually use AD&D rules. New classes like Paladin and Ranger. Bards! New Races--Gnomes, Half-elves,.... Multiclass characters! That wierd section on Psionics at the end. More weapons (the first time I saw a bastard sword). There were so many more options and choices (sounds like 3e, doesn't it). And all the characters seemed so much more powerful than in Basic. 1st level clerics had a spell, and gained bonus spells for high wisdom. Paladins seemed out-of-control.
My first character, IIRC, was a half-elf Ranger/Cleric (correct me if I'm wrong, that was possible under 1e rules, wasn't it?). Pretty much embodied most of what AD&D offered players that was not in basic D&D--New class, new race, multiclass, cleric with spells at 1st level). I don't remember much more, but I think I went on creating characters well into the night....
BTW, I did continue to run campaigns with Basic &D as the core system for a while, using what I liked about AD&D. I guess that was the reverse of the usual trend.