Until a few short years ago, the best solution for creating a 3D comp with particles in After Effects was using Cycore's Particle World; a bundled plug-in that is included in Professional editions of After Effects. There are few people that will bash Particle World. For many it still is the go-to source for creating dynamic particle effects in 3D comps. But few would argue that Particle World is the end-all of particle creation systems. In fact, whenever I want to make a quick and customized particle effect I usually jump over to Apple Motion. The particle effects in Motion have always been far easier and more customizable than anything After Effects offers.
At the default. Particular looks like any old ordinary Particle Generator.
I first became interested in Trapcode's Particular after seeing a tutorial about how to create the cool colorized streaklets made famous in an Ipod commercial. The tutorial showed me how easy it is to make a customized particle and adapt it into 3D space. Particular 2 not only improves upon the features displayed in that tutorial but even caters to that audience by offering new features like a Streaklet particle (eliminating the need to custom-create a streaky particle) and enhanced 3D functionality and rendering capabilities.
Some of the presets get you started quickly making some really awesome effects.