Really happy with this, for £25 it's a good little upgrade for my laptop - I've noticed a decent improvement in both cooling and sound quality. The lapdesk itself feels well made and looks sleek, as you'd expect from Logitech.
I have a 15.6" laptop, which is larger than the product is designed for, but as other reviewers have stated, it fits just fine (though it's worth noting that a 17" laptop would definitely be too large). The lapdesk is just a little larger than my laptop, so the laptop does cover the speakers but I don't see this as an issue. I wouldn't have wanted it much larger anyway as it would have been too bulky and cumbersome for my liking. I simply wanted a light, flat surface to place my laptop on as airflow was poor when the laptop rested on a soft surface (i.e. me!). It does the job perfectly, and the soft cushiony underside makes it nice and comfortable to use. In fact, I've noticed that having the laptop slightly raised makes laptop use more comfortable in pretty much all positions.
The inbuilt speakers make it WELL worth spending the extra 10 quid or so on this compared to other models, and the volume controls are really handy, particularly when in full screen applications such as games. The only thing that would improve this would be a driver to control the levels of bass etc. There are some preset options available if you look for them, but greater control would have been good.