pros:

• the easiest and quickest solution to perform where no trim needs to be removed whatsoever
• full instructions provided with pictures and a video of the install process
• fully reversible, either temporarily via switch or by just removing the harness and returning car to factory state
• it only cuts the power to the lock and not the ecu. When pulling the fuse the power is also removed from the ecu. Some have speculated that this has no downside and that appears to be the case except the delays in starting that many have seen.

cons:

• it costs $50

pros:

• there is nothing to buy
• it is also reversible - just put the fuse back in

cons:

• although straight forward, it is not as quick and easy to install as the harness. Some have broken clips etc and you do need to be careful, but to be completely unbiased many have done this without issues.
• as mentioned above it does appear that this solution does sometimes cause delays in starting. There are theories that the ecu will learn and adjusting for this and that might be the case. However, typically with ecus they learn by acquiring data and if that is the case it would normally log that data. The data the ecu would be logging is that it issued a pulse to activate the relay but didn't receive the confirmation via the positive feed from the relay to the ecu. If it is really doing this i would expect this data to be presented/reported when a consult unit is attached by the dealer. To date no one has confirmed if this happens or not.