Ha ha, yeah, "living" or "to live".   But never "To living" ...  Thanks Dale for pointing that out.   Might have been a typo. 

  Back to the initial question:

"What's IT like downtown?' - not advisable, use
"What´s downtown like?" instead.

What is it like? if somebody have just said e.g. "I live in downtown."

I replaced "Rio de Janeiro" for "downtown" here.
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       Speaking of downtown, it is not advisable to say that way with
"downtown" in a general way, but you can use it freely if talking about a specific (ied)   downtown, say, for example:

What is it like living in Downtown LA?
What is it like living in downtown Memphis?
What is it like in Downtown Miami? (a bit informal, but then, it have the preposition IN, what denotes living IN some place)

What is it like living in Berkeley, CA?
What Is It Like To Live In Downtown Boise, Idaho?

What is it like in downtown Lansing? (Again, it is used, but not the standard.  Anyway, be ready to listen or read it like this)

What is it like to live, work and play in Uptown Minneapolis?