The Valuation was never intended as a census substitute, and if the 1851 census had survived, it would have little genealogical significance. As things stand, however, it gives the only detailed guide to where in Ireland people lived in the mid-19th century, and what property they possessed. In addition, because the Valuation entries were subsequently revised at regular intervals, it is often possible to trace living descendants of those originally listed by Griffith. (See Valuation Office Records)
The Surnames section of this site provides counts of the number of households of a particular surname recorded in the counties and civil parishes of Ireland, based on the returns of Griffith's Valuation.
As you step back further in time, one of the alternatives to census records are the tithe applotment records. The applotment books for each parish give the names of the occupiers, the amount of land that they held and the value assigned to it. The owners or lease holders were required to pay a tithe to the Church of Ireland.
IRISH ESTATE RECORDS
By 1841 the property had been split between Thomas and Richard Nevins so that they both had 11 acres. Some of the adjacent lease holders are named as well as the names of some adjacent townlands. My ancestor, Thomas Nevin left Ireland nine years later so this shows the land that he left behind.
This is how the land looked in the 1860s from the Ordnance Survey maps for the Griffiths valuation at the askaboutireland.ie site. The parcels that are labeled 3A and 4A are the Nevin parcels. Parcel 5 is the bog.