The use of a phase field to describ e interfacial phenomena has a long and fruitful tradition. There are two key ingredients to the method: the transformation of Lagrangian description of geometric motions to Eulerian description framework, and the employment of the energetic variational pro cedure to derive the coupled systems. Several groups have used this theoretical framework to approximate Navier-Stokes systems for two-phase flows. Recently, we have adapted the method to simulate interfacial dynamics in blends of microstructured complex fluids. This review has two ob jectives. The first is to give a more or less self-contained exp osition of the method. We will briefly review the literature, present the governing equations and discuss a numerical scheme based on different numerical schemes, such as sp ectral methods. The second ob jective is to elucidate the subtleties of the model that need to b e handled properly for certain applications. These points, rarely discussed in the literature, are essential for a realistic representation of the physics and a successful numerical implementation. The advantages and limitations of the method will be illustrated by numerical examples. We hope that this review will encourage readers whose applications may p otentially b enefit from a similar approach to explore it further.