Rather than Charles H. Kahn's 'The Art and Thought of Heraclitus: An Edition of the Fragments with Translation and Commentary' (ISBN: 052128645X), I would suggest that those who are interested in acquiring an edition of Heraclitus which gives them the Greek text with translation and commentary look for a copy of Philip Wheelwright's possibly more interesting Heraclitus
I would also suggest that the more scholarly inclined turn to Thomas McEvilley's The Shape of Ancient Thought: Comparative Studies in Greek and Indian Philosophies where, in Chapter Two, 'The Problem of the One and the Many,' they will find a fascinating treatment of Heraclitus which goes far beyond anything Kahn has to offer. On page 149 of this same book they will find a valuable footnote (92) which will provide them with a good idea of the quality (or lack of it) of Kahn's 'scholarship.' (Readers might also care to read my Amazon review of McEvilley, 'Throwing Light on the Landscape of the Orthodox', April 12, 2007).
As for the general reader who simply wants to read an English translation of Heraclitus, their needs will perhaps be better served by a book such as Guy Davenport's 7 Greeks which gives an excellent translation of the complete fragments:
Davenport's translations really are superb and the 124 fragments he gives us, which are tragically all that remain of Heraclitus, take up a mere 12 pages of his book. As a bonus, the remainder of '7 Greeks' is devoted to equally fine translations of Archilocus, Sappho, Alkman, Anacreon, Diogenes, and Herondas.
Davenport's Heraclitus is pithy, pungent, and very much to the point:
16. "Awake, we see a dying world; asleep, dreams."
82. "Defend the law as you would a city wall."
97. "Life is bitter and final, yet men cherish it and beget children to suffer the same fate."
107. "Having cut, burned, and poisoned the sick, the doctor then submits his bill."
Another of Davenport's 7 Greeks, Diogenes, was for me a wonderful find and I'm still chuckling over this one:
Diogenes 109. "I've seen Plato's cups and table, but not his cupness and tableness."
The affluent student who simply must own every edition of Heraclitus should by all means acquire Kahn (and also McEvilley who translates and comments on many of the fragments). Others may find Davenport's translations adequate to their needs, somewhat more memorable than Kahn's, and his book better value for money.