It can effectively make any combination of your synths and / or effects stand-alone, free from the complexity and CPU drain of Cubase et al. These 'chains' can also be accessed through your favourite host by using Chainer as a plug-in. I bought it for live use but have found myself constantly using it on my main DAW. It can even host multiple instances of itself what's the point of that then? Well, suppose you find a combination of synths and effects that sound awesome together (with strategic mixing and panning) and you want save the 'chain' as a single preset.
You can do this very easily and recall the preset in a couple of clicks, run it alongside an existing chain or on a different channel, load / save the same configuration under Cubase or FL Studio and so on.
If like me you occasionally take a semi-modular approach to your plug-ins (like layering several instances of Synth1 for example) these features come in very handy. It functions very well as a lightweight host, but its strength is really in the ease of editing and routing / automation possibilities it presents.