Whether or not using a hand sanitizer instead of regular soap is better could depend on the definition of "better." An alcohol-based hand sanitizer does kill more bacteria in a shorter time than most hand soaps, but true effectiveness is not always measured by sheer volume of dead bacteria. There are other contaminants to consider, and a sanitizer may not address all of them as well as soap and water can. Using a hand sanitizer is definitely better than using nothing at all, but a good hand soap can be virtually as effective under the right conditions.
There is one kind of soap, ironically, which is not generally considered to be as effective: antibacterial soap. These products use chemicals, often triclosan, to kill bacteria on the skin's surface. At first this may sound like a good thing, but triclosan needs a significant amount of time to become effective, not the usual 30 seconds most people spend during the handwashing process. A liquid hand sanitizer, on the other hand, remains in contact with the skin long enough to allow the alcohol or other sanitizing agents to finish the job of killing off harmful bacteria.
Regular soap actually works in two different ways to remove surface dirt, bacteria, and other contaminants. A fatty ingredient bonds to the contaminants and skin oils, while a detergent breaks the surface tension and allows water to wash away the suspended particles. This can have a drying effect on the skin, and many beneficial bacteria are also washed away in the process. A liquid hand sanitizer, on the other hand, chemically destroys bacteria without washing away the skin's natural oily layer. With most products, no rinsing is required.
There is also the consideration of perfumes and deodorants present in bath soaps. While most designed for handwashing are lightly scented or unscented, some may leave behind a strongly residue. This could transfer to utensils, food, and beverages through normal handling. Almost all hand sanitizer brands are unscented, although they still may have some kind of scent. Still, sanitizers should not be able to transfer an unpleasant taste to food or drink. It should be given enough time to dry thoroughly, however.