Most traditional brokers sit with information right infront of them, with live updates from the exchange floor to ensure their cusomters that they have correct information. The huge advantage of online brokerages is that they provide all kinds of statistics and information about different securities within just a few mouse clicks. Looking up a stock's price over the last month, with moving averages and trading volumes, takes only a few seconds for the investor, but there is no communication between the investor and the broker. The investor must rely on what he sees on his screen, which is more like driving a car without windows, you just hope you are going the right way. Most internet brokerages offer toll-free customer service lines though, but the investor is more likely to be put on hold than getting to speak to a representative.
Traditional brokerages are for the most very responsive to their customers.
Many brokerages have many phonelines so the investor is helped as soon as possible, often right away. Phonelines are extremly reliable, they are quick, and the broker has clear communication with the investor. In case of an uncertainty about an order, the broker can simply ask a the investor a question or two to make sure he will place the correct transaction. When investing online, you are first required to have access to a computer. This is not very likely for the investor, but it is possible.