I have a WSM 18 that I keep at a buddy's house for when we want to hang out over there. I've done many, many cooks on it. I think it produces great results, it's a high quality cooker, at a low price. It's perfect for learning temp control, getting used to cooking with charcoal and lump and wood, and being introduced to BBQ in general.
I find the format less convenient in terms of fitting the protein in there versus something like an offset or pellet pooper, but if someone wanted to get their feet wet in BBQ and asked me what to pick up... it'd be the first thing I recommend to many people.