Reasoning

It's finally at 3, but it was barely used at 2 and I don't expect a big change in it's viability.  It's too risky.  First of all, this card becomes a -1 if the opponent guesses right (they usually guess LV4, which is the best level in the game anyway).  And after you use it once, what level to declare becomes even more predictable.  You also need to tailor your deck to accommodate this card by running monsters of different levels (which was good for the Synchro era but bad for an XYZ era where having lots of monsters on the same level is good). 

Good for eccentric fun decks (like Phantom of Chaos), but not consistent enough for tournament play.  Maybe it'll find a good deck again someday, but not right now.

2/5

Reasoning is a fun card to play with, and has also seen it's share of time at various status on the Ban List, currently Unlimited.  Honestly, as far as I'm concerned, Reasoning holds most of it's power in Traditional format, with various One Turn Kill Decks it can be used and abused in.  It doesn't do a great deal on it's own, even in said Decks, it's a combo and set up card.  It can still do the latter in a Constructed Build in Advanced, but it's not anywhere near the threat it has been in the past.  I can't see it being used for much more than fun giving all that goes on in the now.
 
Ratings:

Traditional:  3.25/5 
Advanced:   2.25/5 
Art:  4/5

Reasoning was Limited a long time ago because of Diamond Dude Turbo if I’m not mistaken. That Deck (and its derivative, Airblade Turbo) could use Reasoning and Monster Gate to tear through the Deck blindingly fast and get to whatever it needed for a swift OTK. The Deck was so efficient at what it did that even today you’d probably be hard pressed to find someone who doesn’t consider Airblade Turbo one of the top Decks of all time.
 
Of course, the Deck isn’t relevant anymore; not because of power creep, but because the banlist utterly slaughtered it. Most of the major pieces of the Deck (Stratos, Dimension Fusion, Dark Magician of Chaos, etc.) rest on the Forbidden List, and at least one of them (Dimension Fusion) really shouldn’t come back.
 
As such, Reasoning has no place on the banlist. Apparently the card has applications in the upcoming Infernoid Deck, but I haven’t looked into that so I couldn’t tell you.
 
Rating: 2/5