With the recent installation of my new appradio equipped Pioneer head unit I decided to try out the supported APP DashCommand.
DashCommand - Palmer Performance Engineering, Inc.

I purchased the OBDLink MX blue tooth scan tool through amazon but here it is on scantool.net
ScanTool.net LLC - OBDLink MX Scan Tool | OBD Interface | App Accelerator - ScanTool.net

Here's a look at what came with the unit:

The unit came with it's own Android App and windows software but I have not tried either one so I can't comment on them.

Here's the OBDLink MX installed in my 14' WRX Sedan:

Blue tooth connection to my Samsung Galaxy S4 was pretty straightforward... Plug the unit into your ODB-II port, hit the button and have your phone scan for it... select to pair with the tool and you're set. DashCommand connects when you start the app:

One thing that makes sense but is a little annoying when I'm running DashCommand through my phone to my head unit... You have to disconnect the phones blue tooth connection to the head unit before it can connect to the OBDLink MX... Once I did that my phone connects without issue every time I start the app.

So far I have only played with the app for 20 miles or so but I really like it... It seems very responsive and accurate as far as I can tell (Comparing RPM's and MPH etc) I found some WRX themed dashboards for it on Home - DashXL.net that are fun although the HP and Torque gauges don't seem to work when they do in the default "Tuxedo" dashboard.

Here is the main screen of the default dashboard:

This is the boost only gauge in the WRX dashboard:

Few other default screens:

Since I don't plan to mod the car for a while this seemed like a cool way to see boost and other things going on with my car without investing in a AP just yet... There is an option to data log and it can also read and clear codes... I'll update this thread later when I have a chance to check those features out...