Pretty much par for the course
I think your experience is pretty much standard for any fixed wireless broadband provider. I'm with another such provider up here in Auburn, and my experience is no different, and I'm paying over TWICE what you're paying for one of their "Business" plans.
The bottom line here folks is that all of these fixed wireless providers operate on incredibly small margins. I spent over an hour on the phone one evening with the owner of my provider, who's been in the ISP business for over 30 years. Most are family owned. They source their incredibly cheap equipment from eastern block countries (not from big networking equipment providers like Cisco or Motorola), and therefore get little to no support on it. They run VERY light on customer support, and they don't have a ton of bandwidth to work with on their backhaul circuits.
And the simple truth of the matter is that it's a wireless technology, subject to all kinds of interference. I sell enterprise-level wireless networks, and I can tell you from experience that someone running a microwave in a break room can bring an entire section of a corporate wireless network to a screeching halt, so you can just imagine all of the various things out there in the air that could possibly interfere with a signal trying to get to your home from a tower ten miles away, not to mention the effects of weather.
I love living in the country and wouldn't trade it for a million bucks, but one of the trade-offs is crummy Internet service. I guess those of us who can actually even GET fixed wireless in our homes should probably consider ourselves lucky.
Oh and one comment on the VoIP issue. I'm not familiar with OOMA, but I'm a Vonage customer and most of these types of services offer something called single number reach, also called Multi-ring. Basically when someone calls your home line, it also rings whatever other numbers you specify. I've got our Vonage account setup to ring both my mobile as well as my wife's mobile, that way even if our Internet's acting up, we still don't miss calls. If OOMA doesn't offer it with their basic service, they probably have a premier service that has it.