The version in 4 volumes by Jowett (Oxford) is the standard. It contains
good introductions.
The _Republic_ has been translated by Davies and Vaughan.
Two volumes in the Loeb Series have appeared.
A new method of translation of Plato is needed. The text should be
clearly divided into sections; the steps of the argument should be
indicated in a skeleton outline. Until this is done study of Plato is
likely to cause much bewilderment.
_Plato and Platonism_, by Pater, is still the best interpretation of the
whole system.