Decided to give this a try. Picked up all the parts on Amazon for about $20 shipped.
Got the elm327 today in the mail and gave it a shot. Having read a few reviews of people online who couldn't get it to work at all on any vehicle, I made sure that I got some readings on the free version of the program before purchasing the pro version.
Let me just say, the pro version is completely worth it. It's literally plug and play. Plug the elm327 into your obd port, enable bluetooth on your phone and in a matter of seconds they're synced up.
Others mentioned that they've had performance issues on their phone. I'm using a Galaxy S3 and have no issues with it.
One thing I did notice was a performance difference between my vehicles. Hooked it up on the XJ and it was somewhat jumpy and sluggish to respond, but i've noticed my XJ (and older OBD2 Jeeps in general) have always been slow to talk to even the basic scanner. When I hooked it up to my 06 Acrua, I noticed a much smoother and faster response on the program.
Now....to get familiar with all the features of this program. For approx. $25 including the $4.99 cost of the app, you really can't beat this. Plus, my buddy who's had this for a while didn't have to buy it again when he switched phones last month, so no need to buy the program again when you upgrade your phone in the future.
The only problem i've had....getting the software to install on my computer with Windows 7. Not long after it gets started, it throws an error and aborts the install. I'm going to mess with it some more and see if I can't figure out why it's doing that. It'd be great to log some of this to my computer when i'm working in the garage, but if not...at least it works on the phone. Logs can be saved on the phone and e-mailed.