First:
Good deal or piece of junk? Piece of junk. The unit is known as the ECB aka El Cheapo Brinkman. Not only is it not very good, the price you're showing us is on the high side.
Second:
Why do you need a smoker as well as a gas grill? They do different things. Grill is not barbecue, and vice versa. Now, you can barbecue after a fashion in a grill. Not conveniently, not well, but after a fashion. Some smokers make pretty good grills. One of the nice things about the WSM in particular is it's utility as a charcoal grill.
Third:
Supposing you decide to add a smoker -- and you should -- WSM or something else? There are two best choices in the small smoker category. One is the WSM, the other is the Bar B Chef Offset.
The WSM is the easiest smoker to learn, one of the easiest and best to use. It's very portable and converts to a damn good direct heat grill. Compared to other "water smokers" (aka bullets) ... well there is no comparison. Not only is the WSM far and away the best of the bullets, it's the only one that can really be considered a serious barbecue. Downsides are it's hard to clean, it's just a bit too small to handle ribs comfortatbly, it has a small firebox which means it's sensitive to bad wood and can oversmoke, and it just doesn't look like a smoker.
The Bar B Chef Offset is a smallish offset smoker of the same dimensions as a number of competitors including the Silver Smoker, the Char-Griller Smokin Pro, the New Braunfels Hondo, etc. However the Bar B Chef is much better built than any of the competition, heavier steel, to tighter tolerances, and has the "basic mods" already done. The Bar B Chef certainly looks like a barbecue. It's large enough to handle ribs comfortably. However, despite its appearance it does not do a good job of direct heat grilling (firebox too tight), the size of the firebox is small enough that it's also sensitive to bad wood, it weighs in the neighborhood of 250 pounds -- so it's not portable, it's got a steep learning curve, and until you learn the ins and outs of fire management it requires a lot of tending.
If you're interested in smoking meat -- don't fool around, get one or the other of these.
