How was Oliver Twist a success for Dickens?

There are a couple of ways that this book was successful
for Dickens.  First of all, it was Dickens's first novel but it was published in
installments.  Most of the Dickens books we have today were published in serial form in
newspapers or magazines.  Dickens had been a court reporter and had published several
successful sketches under the pen name Boz.  Some of these were published as a book in
the form of The Pickwick Papers, which was wildly
successful.

Little Oliver was also a huge commercial
success.  He was popular and made a name for Dickens.  Although this is one of Dickens
strangest and most imperfect novels in a way, it has a storyline and characters so
captivating that it is still one of Dickens's most popular
books.

Another way the book was successful was in its
impact on the social conditions Dickens was trying to bring to the public's attention. 
The book addresses poverty, the cruelty of the Poor Law, the inadequacy of the justice
system and the rampant nature of crime.  What an ambitious first book!  Dickens managed
to do the impossible.  He humanized beggars and prostitutes.  He got the prudish
Victorians to consider the lower classes.  Eventually, the book was instrumental in
getting the Poor Law revoked.