Every block has a new way for basic Swamps to tap to kill creatures – though usually not their own spawn, mind you -- and every block has some kind of damage prevention. And as far back as I can remember, anyway, every block has had a take on cheap card selection.
The first disempowered Ancestral Recall, back in Ice Age, was a pretty clear attempt to "fix" a good, but overpowered card. Ancestral Recall was quite exciting but more than a decade of Magic development has taught us that three cards is more in the four mana sorcery ballpark than one mana instant zone. Brainstorm was exactly Ancestral Recall… except you didn't get to keep two of the cards you drew. Back in the first real block, Brainstorm paled in comparison to the original. I remember when Ice Age appeared, discussing the merits of Karplusan Forest or Adarkar Wastes with Worth Wollpert. "Trust me," Worth said. "They're not the real dual lands... but they're not that bad." Worth was right then, and as with Ice Age's pain lands, Brainstorm turned out to be more than okay itself.
A year or two after Ice Age, Magic players in California and Pittsburgh discovered the technique of shaving mana and instead playing low mana cantrips to smooth their draws, to ensure land drops even without actually playing those lands, and to give themselves more robust long games. In the springtime of 1997 or so, the cards in competition for top cantrips were the aforementioned Brainstorm, and Impulse from Visions.
Both cards, both strong, were the best low mana cantrip tools of their shared era, which was probably the high point of this sort of card in Standard. Brainstorm was reprinted in Mercadian Masques, Accumulated Knowledge eventually proved itself a fine successor to Impulse (better, even, in some decks), but for the most part, players since the Golden Age of Cantrips have had to content themselves with half-Impulses like Opt, essentially vanilla options like Obsessive Search or Reach Through Mists, or sorcery speed selection like Sleight of Hand or Serum Visions. There's nothing wrong with any of these cards, of course… But old timers just don't consider them the same.
This new card isn't Brainstorm or Impulse, and it probably isn't quite as good at specifically what Brainstorm or Impulse were about as either. However Telling Time combines elements that are reminiscent of both cards, and combines those elements effectively. Like Brainstorm and Impulse both, Telling Time nets a player exactly zero cards: you invest one card and you get one back. You break even, but have looked at more cards and have better control over the development of your mana and game. Like Brainstorm, Telling Time lets you look at the top three cards of your library. Like Impulse, it costs . Like Brainstorm, Telling Time lets you put one card on top of your deck, and like Impulse, Telling Time lets you put one on the bottom.
Now specifically as a digging card, Telling Time isn't as good as Impulse because you only get to look at three cards rather than four and you only get to put one card on the bottom of your deck rather than three. It is in a strict sense inferior because Telling Time puts one card back on top of your deck... But at the same time, one of the annoying things about Impulse was that if you saw two cards you liked, you could keep only one. If there was another card you liked, Impulse made you put it on the bottom of your deck anyway! Telling Time does not.
On the other hand, Brainstorm has shown us that it is sometimes nice to know the top card of your library. More than just keeping a card that you might like, Telling Time can work in conjunction with a creature card like Dark Confidant -- Bob Maher's new Invitational card, also making its first appearance in Ravnica -- Telling Time's "Brainstorm" aspect can put a land on top so that you don't lose any life for drawing extra cards.
As Brainstorm proxy, Telling Time is more expensive... but also conditionally better than "just" a Brainstorm. One of the things that I always found annoying about that strong card was that sometimes I would simply learn that there was no land on top of my deck and that there wasn't going to be any land in my hand for the next two turns. While it is nice to sometimes keep a card (which was impossible with Impulse), not being forced to keep two cards is a nice compromise.
Now what about the mechanics of Telling Time itself? What does this card represent that differentiates it from the classics?
First of all, looking at three cards is kind of a magic number in 60 card Magic. Most decks play greater than 1/3 lands, so looking at the top three cards of one's deck will generally let a player ensure his next land drop. In the case of Telling Time at the end of the opponent's turn, you can set up your next land drop and set up the most relevant action spell for the next turn. While Impulse was great at finding a land or finding a counter, it could not simultaneously do both things.
At the end of the day, I think that Telling Time will see significant, if not universal, adoption. It isn't going to be an automatic inclusion in every Blue deck, but Telling Time definitely has a role to play. It will make the Wrath of God show up a couple of cards early and might just find the Counterspell when all hope seems lost. If there is a viable combo deck that includes Blue in Standard, Telling Time is likely to make the cut as well.
But hey, only Time will Tell.