Area varies. Look up Ontario on Google and map it. Do satellite. As you can see, large areas of big tiltup warehousing, etc. that overtook mostly ag. areas, vineyards and citrus. Northwest direction closer residential area, older, lowish income, area close to the north side of the airport Holt Bl. is crappy. Further north, the better. Note that also not too far north, lots of shopping and mild industry/logistics, etc., Ontario Mills, Victoria Gardens, stadium with minor league hockey and basketball teams. Go more or less east, the area is changing slowly from the remnants of low income left after the end of the heavy industry in Fontana.
Lots of money in the area now as with economy picking up, the airport, highway and rail traffic feeds in and out of the greater L.A. basin and even San Diego through Cajon pass which feeds I15 to Nevada and Utah and points north and east and east throguh Banning Pass to feed I10 to Arizona and points east.