I have the GSW 690III and really like it. It's easy to use and the large negatives are great. I carry big cameras so I don't find it too much of a burden. Never had any problem with frame spacing, light leaks or what have you.
For me the biggest drawbacks are the rangefinder (I find it hard to use, although it is the only rangefinder I own) and the crappy retractable lens hood which can be really annoying.