The first year I studied Latin (using an early edition of Wheelock) I used the 201 Latin Verbs text, part of the same educational series as the 501 verbs series from Barrons. This book has more substance than that earlier volume, not merely from the 300 additional verbs, but also from additions to the text's introduction. Richard Prior (not the comedian) took the contributions of Joseph Wohlberg (whose 201 Latin Verbs I also own) and expanded and revised those with his own additions for this text.
This is at heart the most basic of basic books. Each of the numbered pages 1-501 has one verb laid out in all its tenses, voices, moods, persons and numbers. The pages are laid out with Active Voice on the left (the most common voice found in Latin writing), and Passive Voice on the right. The page is broken into Mood - these include Indicative (the most direct form of address), Subjunctive, Imperative, and Infinitive. The verb tenses in each of these subsections is laid out in first, second and third person, singular and plural, in a chart. . The bottom of each page lists the participle forms, forms of verbs used as modifiers. There are also alternative forms of the verb, compound and related words, sample sentences showing context - these are not 'fake' sentences, but give the sources (Cicero, Horace, etc.). Each page has one verb dedicated to it.
As Prior indicates, the series by Barrons has the limit of 501 verbs (an arbitrary but useful number) - but, in fact, since there are patterns for verbs (called conjugations), knowing one is often knowing them all; the exceptions to these rules for the various conjugations are certainly included, as are the strange verbs (sum, esse, to be, which ends up being strange in every language, and many others like eo, ire, to go).
Some verbs are not fully developed - the authors explain that while there are theoretical constructs of verbs, sometimes we have no evidence that such tenses or constructions were ever used, and so these are omitted. Also, there are lots of verbs whose construction parallels each other precisely (many verbs are formed from prefixes being attached, much as languages like German also do); these verbs are parenthetically linked to other, similar verbs.
There is an English-Latin index, and a Latin-English index at the end of the book. These indexes are handy, as is the Verb Form locator at the end. The word selection comes from frequency counts of verbs on Latin exams of the New York State Regents and other College Board entrance and/or placement examinations.
There are few additions here - little grammar, no pronunciation, nothing by way of history. This is simply what it purports to be - a book of verbs. In that, it is very useful, and as I studied Latin beyond the first year, an invaluable aid.