I hear you on the range of motion. That was my biggest problem with it. The start of a rep would be really easy, it'd get more difficult through the middle, then really easy at the finish. Never got used to it.
I won't say that the Bowflex is a waste of time as you can still get a decent work out on it. However, it won't increase your practical strength as much as free weights and it won't do it as quickly either. It's a good space saver, but I'd rather work out by other means.
But I also don't think that sitting in a gym 2 hours a day, doing the typical routines, is a good way to increase fitness either.