I've purchased several rolls of different weights, including 2 rolls of this lightweight fabric. I've been using this material a lot for various projects.
>As a liner under my strawberry plants. The roots grow through the fabric, but it keeps weeds from germinating from underneath. You do need to keep new weeds in check. The nut grass is the worst if it gets into the fabric (germinates in the mulch).
>I have saved about a CY of cobbles for future projects. The fabric is tough enough to withstand tossing the rocks on it to keep them clean.
>I've cut an 8 foot piece. Works pretty good for crawling under my mower or truck to do repairs. Compact enough to keep a piece in the trunk too. Guess it wouldn't work out too well if the ground was wet (haha).
The downside is that it unravels easily. I'm sure there is a tool to melt, cut, and seal the edge (somewhere). For me, sharp utility blades and a 4 foot board does the trick.
It also works great for raking up pine needles (6'x10' piece).
I have noticed field ant colonies under the heavier fabric, but so far, nothing under this fabric. Guess the rain drains through it easier.
It is pretty light, so you'd need a few rocks or staples to keep it in place until you put stone or mulch over it.
I have to say that I'd never buy another roll of heavy fabric again, unless it was for my driveway.
Hope I've given you some useful info.
Nicholas 
