They are good for use with pens, pencils and ink washes.
Markers have minimal bleed through to the opposite page.
Here, I've used Derwent Inktense coloured pencils. I applied the water afterwards and there was warping. It's not recommended to use this paper with any sort of water medium. The paper warps and since the paper is made of wood pulp, the fibers will come off with subsequent applications.
Here's a comparison between smooth and fine grain heavyweight paper for use with pencils and coloured pencils. The fine grain paper has more tooth and will show more white from the paper.
Two more sketches on the fine grain heavyweight. Ink lines look essentially similar regardless of whether the paper is smooth or fine grain.
These are the best cartridge paper from Daler Rowney in terms of thickness and weight. They perform predictably. Difference between smooth and fine grain would be more obvious when used with dry medium such as pencils and pastels.
Daler Rowney is from UK so you can find their products at JacksonsArt (UK).