Well, there are definitely some cards from it which enhanced deck construction IMO.
But I remember that for a certain time period, almost everyone I came across was playing a threshold or madness deck, or a deck that made heavy use of graveyard abilities (kind of vague term, but it works). That, and almost all the good players (casual players that also played in tournaments somewhat, typically) played Psychatog.
And then I remember another time period in which everyone played decks based around creature types. Elf decks, dragon decks, zombie decks, sliver decks, wizard decks, goblin decks, beast decks...
Well, some people are still stuck in that period, and they're bad players. It was very easy for me to win against pretty much anyone in casual around this time, because they would always predictably play creature-based decks. And then Mind's Desire came out!

Thank Urza's Saga for Arcane Laboratory...
And now...
Now it seems like if I really wanted to, I could stomp on most people I come across simply by using Hurkyl's Recall or Shatterstorm in my decks. Oh, and I should get more Powder Kegs, not because it's a good card, but because I don't know how much longer this artifact-land craze is going to last...
I thought that the game had achieved some amount of balance during the Masquerade cycle, and trusted Wizards too much, thinking they would continue the trend. That was stupid, but new cards still suck!
