I have just finished this book.It is very much of its time and reminds me of EE "Doc" Smith's "Lensman " series; they thought big in those days! I love SF from this period, and although Campbell deals with mind bogglingly large ideas, he is able to make the science sound plausible.If you like SF from the classic period, you'll love this!
I don't know what the other reviewer was looking for, but being very familiar with the SF from this period, I find this series a great example of its type. Sure the characterisation and the plot are shallow, but for galaxy sized ideas and scientific concepts Campbell is your man! These are not quite as good as E E Smith's Lensman stories, but certainly deserve to be resurrected from the literary abyss - they make a really good read; I have thoroughly enjoyed revisiting this classic early period of SF!