Product review (4 stars): Some assembly required...
Pros: Same exact counter top dimension as the 25-year-old GE Profile downdraft cook top this replaced with.  Assuming that you can reuse the existing electrical wiring and venting ducts, the installation is a simple DIY task.

Cons:

1) This unit does NOT come with a bracket to secure the cook top to the counter. Read the manual online and order the brackets and screws if you plan to secure the cook top to the counter from below.  The default installation relies on applying thin rubber gasket around the edges of the glass cook top  to hold the glass in place on top of the counter with the gravity providing the grip

2)  This unit has vertically  longer fan module that extends about 5-6 inches lower than the old model.  The impact is that you may NOT have enough space to route the duct  and you may end up having to cut into existing floor of the counter shelf.  Read the installation manual online first and measure before you buy!!!  I had to make some cuts into the floor board of the counter shelf and come up with a creative use of the standard 6 inch flexible venting tube.

3) Supplies you should have ready:  3.25 x 10 in to 6 in transition duct (not included), standard 6 inch flexible duct,  duct tape, drill , wood cutting dremel tool or something similar, power drivers to remove the old unit... and a lot of patience.