We've been staying there since before they decided to call it Old Key West. (only in the past two visits we've started broadening our horizons). It's one of the more secluded resorts, which fits the theme anyway. (As long as you don't get a room near the road. You almost forget you're in WDW at this resort and feel as if you're on a "lazy" vacation instead. For some reason it never feels as crowded as the other resorts and when you're walking around you feel like you're the only one there.
The rooms are also different from any other resort on property in terms of layout. They're not the typicical "box-shpaed" rooms. They feel more like condos. Even the studio is a V-shape than a rectangle. (I think the studios are also bigger than any other studio by quite a few feet). They feel really "home-y" to me, but maybe it's just me.
The resort itself is small and you could probably walk to the Hospitality House in under 15 minutes from anywhere in the resort. The roads are also smaller compared to the other "condo" style resorts. Only the best bus drivers service OKW

. It's got one of the craziest bus routes ever... they learned their lesson for the later resorts. I guess the small streets matches the Key West theme though.
The location isn't as ideal as the beach club because you'll have to take buses everywhere. In the last few years we've stayed at OKW (probably starting around 2000) the buses in OKW have had terrible timing issues.
The people who stay at OKW, for the most part ALWAYS stay at OKW, and it doesn't get many "outside" people. It's my dad's favorite, but ever since staying at the yacht club it's been a toss-up for me: Location versus experience. I love the nostalgic feeling of the place. It's probably one of the only resorts with an in-depth backstory. I'd say it's the equivilent of a tropical Main Street USA. I guess a lot of people wouldn't consider it heavily themed, especially locals, but for us northerners, it's a real treat.
Basically this is Disney's quiet resort.