This is a great way to get a first book published BUT there's also problems.
1 Cost - It costs money. Each order you place for books has to be paid for, plus the initial costs for setting it up for printing. The chances of recouping that money, especially with a first book, is almost impossible.
2 Media Coverage - you need this but again it's very difficult to get the coverage you need. As a self-published author media don't really want to know you. They have enough of the big names to deal with.
3 Agents - trying to get an agent is difficult. They also have big name authors on their books so no matter how good or interesting your book is it's difficult to get an agent. If you want to sell the film rights you have to get an agent.
4 Distributor - you can get a distributor but that also costs you money and you may not get receive enough from sales to cover the cost of supplying your book to the distributor. The exposure is a plus though.
5 Many stores, including Dymocks, will take your book without a distributor but you need to pickup the unsold copies. This way is probably the best but it's only suitable in your city or area.
These are some of the points I've found since becoming a self-published author, so what do we do - we persevere, keep going and hope we can succeed.