One of the major issues that I have with it, is that there is no serious emperical evidence that supports its notion that these types of needs are hierarchal, while there is a lot of indication that they aren’t.
In real life, people often display and pursue needs that, according to Maslow’s theory, they shouldn’t. People that loose their job, for instance, often display increased social needs, rather than those on a security level. They’ll be in a bar. Another example: to many, respect is more important than security and in many (sub)cultures, respect is considered well worth dying for.
The theory is seductively simple and that’s why it keeps coming back, but most complex questions have many simple, attractive solutions that are all wrong and only a few correct, yet complex ones.
Maslow’s theory is interesting and helpful, since it helps us think about what may be the base for people’s motivation. His notion that lower level needs need to be addressed before higher level needs is unfounded, though.
There are other alternatives that are interesting and may offer better explanations on behavior, such as McClelland’s theory of needs and Van Hofstede’s research into cultural differences, but as far as I know there is no single ultimate theory that covers it all, especially no simple one.