It is competitive to get into, for sure. You are likely to need prior work experience to get on to either a graduate training programme or an entry level job. You might find this interview with a marketing consultant useful reading to help answer more of your questions.
generally speaking marketing can be a very fun field to work within. In terms of qualities, you definitely need to have an element of creativity but you also need to be a very good communicator (written and oral), have good planning skills and have a good ability to develop effective working relationships.