Well I added the free DS4 to my 'purchases' at Daz, likely it will sit untouched eternally, but hey.

Issues with DS, and it was what I started with, the crippled rendering engine.  If you require external plugins to make the most out of it, it is crippled.  Firefly might have its faults, but at least it isn't maimed to sell plugins.  3Delight is a beautiful engine, it truly is, but what Daz has done to it is anything but...

Material editor, don't like it, heck I have a love/hate relationship with the Poser mat room, but at least I can get what I want out of it with enough time and swearing.

Plugins, plugins and more plugins.  Realizing you need to shell out another X amount to get it to have any real functionality beyond load, pose, render.  Or buy the advanced or soon to be 'Pro' version.

Proprietary dynamic cloth, no dynamic hair, etc etc.

The list could keep going but I will stop now before I need to start Robyn's mantra too.