maybe not what most cruisers are interested in, but i have been using a Fleet Broadband 150 for racing, and it's great.
the hardware cost is high - about $4500 to $7500 - depending on which model you get, but the per MB data costs are lower than Iridium.
I have had pretty good results with the Thrane and Thrane, which is at the upper end of that range.
Of course, you will use much more data, so don't expect to save any money.
compared with Iridium, it's faster and easier and it means that as navigator i am using my time much more efficiently.
obviously, i am able to view products that otherwise I can't view at sea
I can now look at several global models, not just the GFS, and I can easily get every model run, so that i am more on top of changes in the forecast. With Iridium, I didn't always get every run
I can also get every surface analysis and surface forecast - what you guys call the weather faxes. with the iridium, i tended to use these a little sparingly, even though i think they are very important
some products that i rarely downloaded at sea with iridium - scatterometer winds, and other satellite products are easy to get. also, near shore i can get the 248nm radar.
another big thing is competitor tracking - i miss fewer scheds.
but the biggest difference for a navigator is that making it easier to get the data means that much more time can be devoted to actually thinking about what it means.