I've owned one of the
Ibanez acoustic seven strings ever since they came out. It's great for fingerpicking and solo playing, but it'll require you to relearn chords if you intend on using it to strum on.
Sound wise it really depends on the strings as well as the nut/saddle. I *think* the new ones come with the Ivorex nut/saddle but mine came with a bone nut and a plastic saddle. I was going to sell it off and get a Taylor but I ended up cutting and shaping a new nut and saddle from two TUSQ blanks and now it's a keeper.
I wouldn't recommend buying one if you've never tried an acoustic 7. It's a completely different beast than an electric 7. (unless of course you're doing a "live acoustic" jam of a song that uses a 7 string)