Update 2020 (#2)
As of Solidity 0.6.0, ABIEncoderV2 is no longer experimental.
Update 2020 (#1)
An update from the Solidity team reads:
We are almost finished with implementing breaking changes and can hopefully release Solidity 0.6.0 later this year. Some of the new changes include:
ABIEncoderV2 is no longer experimental.
As you mentioned, ABIEncoderV2 is currently in experimental state. This means that the creators do not vouch for its use in production.
Additionally, there have been two critical bugs(1, 2) found in Solidity surrounding ABIEncoderV2 within the last 3 months (at the time of writing), one being just 4 days ago.
Finally, auditing firms such as Zeppelin have noted the use of ABIEncoderV2 as a "High Severity" item, as they believe it is not ready for production.
With that said, teams like 0x and dYdX are using it in production and have been fine thus far. If you are using ABIEncoderV2 in production, try to limit its use to only necessary items, and attempt to write as many tests as possible for the affected code.