Having used Eagle Creek PackIt cubes for years as well as Eagle Creek PackIt compressor bags, I was intrigued with the idea of having a compression cube and decided to give this a try. Here are my thoughts, in no particular order:

PROs:
- Large capacity allows for either larger or a good number of smaller items to be put in
- Lightweight
- Has some sort of frame that helps a bit with keeping the shape
- Nice color :-)
- Compression works much like those expandable bags with zippers - when the zipper is closed the height of the cube is roughly half of what it was
- Unlike compressor bags items do not need to be rolled up, and no air valves can potentially be blocked

CONs (if you want to call it that):
- Using it with large items leads to considerable deformation of the cube. I put a short down jacket in and while I was able to compress it OK, the cube went out of shape and became 'wavy'
- Works best with items that contain a lot of air, such as down-filled items. I also tried using it with 'regular' clothing (jeans, t-shirts, fleece sweaters/jackets) and found it difficult to impossible to fully get the cube to compress. Most times I ended up with being able to close the compressing zipper only half way for fear of breaking either the fabric, or the zipper, or both.

SUMMARY:
I think this is a good product overall but it is only really useful with certain items that can be compressed well. In all other instances it just makes for a nice, spacious packing cube. I will continue to use it as a regular packing aid but in all honesty don't see it getting much use as a compression cube unless I have very specific items to pack that lend themselves well to compression.