Personally, I always thought I'd hate them. I just thought they'd be cramped, uncomfortable, and make it a chore to play effectively. However, on a recent trip to Indonesia, I did get to play on some and was proven wrong on all counts. Of course, the cabs were in various states of functionality, some with great buttons and sticks with no angles, others with great sticks and stuck buttons, but that's the fault of proprietor, not the cabinet.
My experience, however, is based on the fact that I am not a big guy. I'm barely 5'7". I also never had the chance to play against anyone, so it was always just me at the machine. The wife's tiny, so even if she were to play, I'd still be comfortable. My 6'6" friend, however, would be a different story entirely. All in all, though, it wouldn't matter, because it would pretty much just be me on the machine.
I think that if you plan on having more than one person, though, you should consider sticks with a short throw. The above-mentioned bohemoth would beat me to death with his elbow on an upright Street Fighter Alpha 2 cab, and that was with whatever they used in U.S. cabs. On a candy cab, space is a bit more precious, especially since you can't take a half-step to the side mid-game if you're getting elbowed. The Sanwas, which I'd also never used and figured I'd hate, worked really well, at least on the machines that hadn't fallen into disrepair.
My final verdict on the candy cab was that it was like what I'd always dreamed of when I pictured having a stick for my consoles that wouldn't slide all over the table or flip around in my lap. Sitting down is kind of important, as my knees have been shot since I was 15. Unless I get an upright cheap to MAME out and just use barstools, I'll probably go with candy dimensions when I finally have the time and money to build.
In the end, it's really up to you on the candy cab decision.