Yes, IDL is a very new thing for Poser. Frankly, it was a bit of a disaster when Poser 8 was first released, but most of the problems have been addressed in SR1. Now that it works, it's great - but you'll have to do some work with it.

IDL makes a reasonable attempt at replicating how light in the real world actually behaves (not a perfect one, but pretty good). That means that light sets for previous versions of Poser won't work too well with IDL, and you'll have to customize them or more likely start from scratch. If you're used to Poser 6, you may find some aspects counter-intuitive.

You may also need to modify shader nodes (e.g. deleting / disabling Ambient Occlusion nodes - IDL really doesn't play nicely with them). With IDL, you need to consider the whole environment around your scene, not just what's in your camera view, as the light bouncing off the surroundings affects the final image.

Poser 8 lets you control the falloff from spot and point lights (inverse square or linear) so they behave more realistically.

And so on. Everyone has an opinion about whether Poser 8 is any good or not, but in the end, it's your judgement that counts. There should be enough information in this and the many other threads on Poser 8 for you to reach a decision. The only thing I'll add is that there's a lot of criticism of Poser 8 here, much of it undoubtedly deserved, but bear in mind that there are hundreds of satisfied users out there who won't have posted anything because, to borrow a phrase, 'it just works'.

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