Having no prior experience to tuning prior to owning this car, I have to say that this product has taught me way more than anything else that I have done to the car. When it comes to monitoring the ECU, the gauges are top notch. When mounted on the pillar, seeing your customizable shift lights and other gauges is really convenient. Applying a map to the ECU is quick and painless and only takes a few seconds. The additional functionality of Flat-Foot Shifting and Launch Control are pretty amazing as well.
By all means, the best part of the AccessPort is the consistent support from Cobb. New updates to the firmware brings new features, and updated maps are always on the horizon. At the time of writing this Cobb just announced information for the first release of FlexFuel support for Subarus which is something that I'll definitely be taking advantage of in the near future.
One thing that I would recommend is to not rely on the OTS tunes any longer than you have to. They are a great way to get you by until you've arranged an appointment with a tuner assuming that you are using supported aftermarket parts, but I've heard horror stories of OTS tunes not being as reliable as one would hope.