After reading many reviews of head units I realized that Sigma covered the core set of features with the ROX 10.0 for less than half of what competitors are asking. I recognized that I could live without a head unit that ws a pseudo smart phone game console. I didn't need notification of calls and email or to flip through playlists -- while riding. I also don't want to pay monthly fees for related services or race my ghost self or others live on Strava. If I need routing help, I'm going to use my iPhone anyway. What I really wanted was more training data during my ride but more seriously after my ride.
The ROX is inexpensive because it does away with many things that may be nice but aren't essential: buttons rather than touch screen, old fashioned LCD rather than color, breadcrumb rather than live turn by turn dynamic map and routing, wired rather than wireless data transfer, ANT+ only with no Bluetooth support. If you want those, pay more than double and buy competing models.
The rugged ROX 10.0 covers all the basics in a simple reliable package for modest cost. It also offers one or two features not found on other units -- such as derived power.
There are some rough edges. The starting altitude seems to jump around from ride to ride for no obvious reason. Sometimes it can take one or two extra attempts to get ROX plugged into my iMacs USB port and synchronized with the Sigma Data Center analysis product. You may read complaints about screen visibility but it seems fine to me under most light conditions. When I need better visibility, I flip on the backlight and that works fine. In a couple months of riding, it hasn't lost a ride or delivered garbage data. It has paired easily with my two sensors (Wahoo SC, Viiiiva HR strap). The data correlate with what Strava reports on my iPhone (paired with same sensors but over Bluetooth). I pay no monthly fees to anyone for anything. For deeper analysis I export my data from Data Center and load it into the free Golden Cheetah program which can derive values and slice up data sets more ways that most could imagine (for example, it derives gearing, maps out exertion intervals, renders scatter plot graphs.) Seemingly all ride data are included in the export in a standard format readable by most other products (e.g. Strava). If you have a power meter, you can pair it over Ant+ with the ROX and your data set should include everything available from head units costing hundreds of dollars more.
If you just want core training data and display of standard real time values like speed, cadence, heart rate, distance, etc ROX 10.0 is a compelling value.
I give it 4 rather than 5 stars due to some quirks in the software. In a few months time I could buy an entry level power meter for the money saved by buying this unit and forgoing recurring fee based services. Engineering is about doing more for less; German based Sigma did exactly that with ROX 10.0..