Yes, it is loaded with public domain works. My theWord list runs to nearly 3,000 volumes.
But, it has some very fine "for purchase" works as well. And, as Brent said, it is VERY easy to use and quite customizable.
BDAG - A Greek-English Lexicon of the New Testament and Other Early Christian Literature, 3rd edition (BDAG)
Eerdmans Dictionary of the Bible (EDB)
New American Standard Exchaustive Concordance (NASEC)
Theological Dictionary of the New Testament, Abridged in One Volume (TDNTa)
Theological Wordbook of the Old Testament (TWOT)
IVP Bible Background Commentary, New Testament (IVPNT)
IVP Bible Background Commentary, Old Testament (IVPOT)
NICNT: The Epistle to the Romans (NIC/Romans)
Bible Panorama (revised 2nd edition), The (BBlPnrm)
Expository Notes of Dr. Thomas L. Constable, The (Constable)
My proprietary software (e.g., Libronix, WordSearch, Biblesoft, etc.) is great. But, somehow the free software such as eSword and theWord appeal to me on several levels and are VERY easy to use.