I put the Cat Eye Strada Digital Wireless Cadence computer on my new touringcommuting bike and have logged 1500 miles. It is accurate and has worked well in cold and wet weather. Setup isn't hard, as long as you have the instructions. Buyers need to be aware of two shortcomings. This computer may not work in close proximity to the new LED lights and it seems to use a lot of batteries. I'd still recommend it to a friend as a reliable speed and cadence measure.
I haven't tried using this unit connected to my phone, but the stand-alone functionality works much nicer than the 805 I was using previously. The boot up time, menu operations, touch screen performance, display, and GPS performance were all noticeably improved. It was well worth the upgrade.
The new speed sensor wraps around your wheel's hub and uses an accelerometer to compute speed as opposed to the old magnet-based sensor. It eliminates the annoying tick-tick-tick sound that can occur when the spoke magnet hits the sensor arm when they go off position after a huge bump. Battery life is pretty good, too.
The sensor will wrap flush around most hubs, but certain ones (e.g. curved hubs) will cause it to mount askew. This is only a problem with tight spaces, such as 130mm rear, curve-shaped hubs where the sensor won't mount securely causing erratic data reads. In these situations, it's easier to mount it to the front hub.
Overall, I prefer these type of speed sensors. I just wish Garmin would support Bluetooth LE (BTLE) in future versions.
These new sensors from Garmin are great. There is no fiddling with alignment trying to get the sensors and magnets aligned. Easy to switch between bicycles so only one set is needed. To get the Garmin to recognized the speed and cadence sensor you may need to spin the pedal and wheel. Just make sure that your Garmin Edge can recognize these units before purchase. It works with my Garmin 810.