I wanted to wait a good while before reviewing this, as it's important to live with a product like this before passing judgement. It's been almost a year now since I purchased this at Best Buy. I cook often and make some labor intensive meals, so I'm pretty demanding of my cooktop. This 36" downdraft gas cooktop from Kitchen Aid is worth the money. I'm very satisfied.
Many have questions about the effectiveness of the downdraft. While it's not as good as a traditional over the cooktop hood, it does a good enough job for us. No, it does not get rid of 100% the steam, etc. from whatever you're cooking, but when you don't have the option of a regular hood, this is more than adequate. I've had both hood and downdraft, and honestly, the difference isn't that big of a deal. If you're frying bacon, it doesn't matter if you have a downdraft or a hood, you'll have a similar result. Your kitchen/home will still smell like bacon. If I had to guess, I'd say it's at least 75% as good as a high CFM hood. In other words, it works just fine.
In certain cooking situations, I use a simple trick to divert a majority of the steam or smoke to the downdraft by positioning a lid just off the pan/pot on the same side as the fan. It's pretty effective at catching the bulk of the exhaust. You'll see what I mean if you experiment a little with it.
The downdraft compartment is easy to clean and the fan itself isn't overly noisy, although I rarely use it in the medium or high position. The low works good enough for me.
The smallest burner is great for low, low simmering and the larger ones really put out some heat, boiling water faster than any cooktop/stove I've had in the past. There is plenty of room for multiple larger pots and pans at the same time without seeming crowded.
It looks nice, is very easy to clean and has a sturdy, heavy duty feel to it. I'm very happy with this cooktop, and would gladly recommend it to anyone who's seriously into cooking.