Product review (4 stars): Solid
The tray is nearly perfect for my needs: the built-in tray on my desk was too narrow to fit my wide ergonomic keyboard and have space left for a mouse.  The tray itself is a textured piece of plastic that appears very durable and works well without a mousepad.  The rails are solid, making the tray itself feel very secure.

Installation on an upright desk is a two person job, but if you can flip your desk it would be much easier.  Be prepared to have a drill with a small bit for creating pilot holes.  My only other quibble is that the locking mechanism to keep the tray firmly extended isn't terribly strong.  These are ball bearings, rather than the wheel rollers you might have seen on other trays.

Still, with adjustable height, plenty of width and being quite affordable relative to its competition, this is a good choice.