Anyone stayed in this apartment or used this agency?
www.niceflatinrome.com/otavia.htm
We are looking for someplace safe, clean, and toddler friendly. I'm worried about this being on the 3rd floor

The link you provided seems to have connection problems...?

Anyway, a third floor in Rome has its advantages....ground and first floor levels can be noisy. Also, if there are businesses at ground level, it can get very nosiy early during the day when deliveries are made.

When it comes to apartments or rentals, MY experience is rent from the owner whenever possible....that is why I always first check vrbo.com. I am renting a two-bedroom apartment in Rome this coming May from the owner (recomended from prior guest) and so far he and wife have been wonderful to work with.

The link works for me.

The area is, as described on the web site, right in the Jewish quarter (which is the neighborhood next over from Campo dei Fiori, so very central). Traditional neighborhood, convenient to the tram from the Trastevere station, and overlooking a piazza (della Cinque Scuole) that houses a small parking lot, but the roads around it are not through-ways to anything, and the sidewalks are wide (right there) and even have a fence between the road and the sidewalk. I'd contact the agency and ask about a washing machine (really terrific with a kid along) and elevator---given the price and the location there's almost certainly no elevator. So long as you and your husband are fit enough to make the stairs and get the toddler up them as well I'd be fine with this property.

You can easily see the neighborhood by using google map's streetview of "roma piazza delle cinque scole" (not cinque scuole as it's spelled on the web site---scuole is standard Italian. meaning "schools", and the piazza name is presumably dialect). The precise bit of via del Portico d'Ottavia isn't on the street view, but it's fine.

Oh, and do ask about things like bath tub vs. shower, etc. Agencies/owners often have additional photos that they can send that will show you more detail, and you might specifically want to look at how high up the windows are (from the floor) and whether a child could easily open them.

Does anyone know if this is a reputable agency? I know SleepInItaly is reputable, but they don't have the apartment for the dates with we need at the same price

A very reputable agency is SleepingRome.com, very good prices for apartments in Rome.