LOTS more cars and traffic jams!
Excellent new highways
More reliable trains
No more "faulty" cabinas telefonicas where you can "duro-drop" (drop in a duro and talk with someone in another country for hours, with a line of twenty people waiting behind you to do the same)
Higher prices (especially rent and real estate)
Sprawling suburbs filled with chalets adosados
Increased street crime in the big cities due to a growing drug problem
Cell phones everywhere
More flowers in public areas (in Madrid, at least)
Fewer bars where you can drop your toothpicks, little paper napkins, shrimp shells, etc. on the floor
Banks now keep track of your account electronically instead of handwriting your deposits and withdrawals in a big book, and everyone uses ATMs (Spain is SUPER modern and up-to-date now)
Slightly less bureaucracy
You can find just about anything you can think of to buy in the big cities, regardless of where it was made, since Spain joined the EEC.
No more Yankee Go Home graffiti
More local graffiti
More air conditioning in buses and trains
But really, the important things, like great hospitality, easy-going lifestyle, wonderful food, magnificent sights, great culture, are all still there!