Yes, and no. Raised beds do warm more quickly than those that are in the ground in the Spring, but they are often the first to frost over in the late Fall and Winter months, and can even be more susceptible to frost in the early Spring. Raised beds also drain more easily, meaning they are ideal in wet climates, but a serious disadvantage in dry climates. So, it really comes down to what your particular gardening goals are, and whether raised beds or in ground beds are better for meeting those goals.