I can't really improve on the existing reviews, so I offer some memorable quotations from this novel.
"He was in love with his work, and he felt the enthusiasm for it which nothing but the work we can do well inspires in us."
"But it is the curse of prosperity that it takes work away from us, and shuts that door to hope and health of spirit."
"[E:]ach one of us must suffer long to himself before he can learn that he us but one in a great community of wretchedness which has been pitilessly repeating itself from the foundation of the world."
"The house of mourning is decorously darkened to the world, but within itself it is also the house of laughing."
One thing I should mention: William Dean Howells' prose is much more accessible, and easier to read, than that of his friend and fellow Realist writer Henry James.