The "501 Spanish Verbs" book proved enormously helpful when I was studying Spanish. So, when I switched temporarily to German, I bought "501 German Verbs". Imagine my disappointment when I read the very first entry: "abholen", to see that the pluperfect conjugation is incorrect:
ich hatte abgeholt
du hattest abgeholt
er hatte abgeholt
wir haben abgeholt instead of wir hatten abgeholt
ihr habt abgeholt instead of ihe hattet abgeholt
sie haben abgeholt instead of sie hatten abgeholt
There's a similar error for "ausgeben".
These early errors don't inspire confidence. But if you mark and correct those entries, and watch for any other errors in the book, you'll find this book a wonderful resource.
I haven't spotted other errors in the book, but that doesn't mean that they don't exist.