Do you think coalition governments can be effective? What are some of the benefits and drawbacks of the coalition governing model?

Coalition governments, also known as consociational, or power-sharing governments, can be effective in the right circumstances. 
This type of government is popularly seen in Europe, in countries such as Switzerland and Ireland. The main benefit is that it gives members of the government from different ideologies the opportunity to work together in order to represent a larger portion of the population.
A strong example to back up the use of a coalition government is the case of India. India is comprised of 29 states, each representing a distinct culture, language, and history. In order to respect these differences, each state has some autonomy in its ability to create laws and establish an official state language and education system, among other factors. This has eased tensions between the states and the federal government, and the representatives of each state in India have the ability to speak for their states in the national government as well. This has all resulted in a stable Indian government where there is generally great pride in not only the home state of Indians but also in the idea of being "Indian" in a national sense as well.
Drawbacks to coalition government can often be seen when there are great ethnic or religious divides. One type of coalition government is that of "proportional representation." This is when, for example, there are two ethnic groups in a country--one has a larger population than the other: the group with a larger population will have a larger representation in the government (proportional to its population size). When there is already hostility between the two groups, this type of representation can spark outcry and often violence from the smaller and less represented group. In response to this initial upset, the other group will often react with violence as well, leading to war and/or a complete breakdown of the government. 
An example of a failure in a coalition government is the case of Lebanon. The power was divided between Christian, Sunni Muslim, and Shi'a Muslim populations in the 1940s. This arrangement unfortunately ended in civil war.
So in some cases, coalition governments can be effective, but there is always the risk, especially when forming a coalition between sensitive divisions, that the end result will be violence and war.