Oracle of Mul Daya is still quite strong. It provides two very powerful effects - ramp from hitting extra land drops, and card draw by playing those lands off the top of your deck. Throw in synergy with shuffle effects and you have a very powerful engine card. Aside from the previously mentioned shuffle synergies, I'll note that Oracle also works well with topdeck manipulation -
Brainstorm effects,
Sylvan Library,
Scroll Rack,
Sensei's Divining Top... Oracle gets way stronger with support. Also works well with
Crucible of Worlds effects for extra ramp off fetchlands.
That said, it does have some downsides. For one, revealing every card you draw is a significant downside for some decks (and annoying in general). It's also less consistent as ramp than something like
Cultivate or
Skyshroud Claim - if you don't have some way to manipulate the top of your library or get extra land drops, it can occasionally do nothing. That's not unique to Oracle though - as a value engine, it shines more when it sticks around for a while. I've definitely noticed it functioning better in my Tasigur (control) deck than Samut (combo). I do think it's still worth playing without shuffle effects / topdeck manipulation, but it certainly does get worse.
Anyway, was very happy when it got a reprint, but could still use a few more. Pretty much every
Exploration effect is obnoxiously expensive, as are all the good topdeck manipulation effects. I'll call out
Courser of Kruphix as a cheaper alternative, but it is a significant downgrade, in my experience.