2011 was not a good year for OCZ. Regardless of whether it was justified or not, the Vertex 2 and 3 were shredded in forums with stories about the SSDs suddenly malfunctioning. OCZ's reputation was dealt a big blow. The image of the SandForce controllers used in the Vertex 2 and 3 was improved somewhat this year, when Intel introduced its 520 series SSDs with the same controller. When Intel decides to use a certain type of controller, you can count on it that the initial problems with it must have been resolved.
Still, OCZ must quietly be hoping to slowly end its SandForce chapter. The fact is that the newly introduced Vertex 4 no longer uses SandForce, and instead has a controller that was developed in-house. Last year OCZ acquired Indilinx, which SSD controllers, and OCZ recently introduced the Octane and Petrol SSDs, which are based on the Everest controller. These didn't set any records, but do have a very good price/ performance ratio.
The Everest controller has been further developed and tuned at an impressive rate, resulting in the Indilinx Everest 2 that now serves as the basis for the Vertex 4. The intrepid researchers at Anandtech have determined that this Everest 2 chip is actually the next generation Marvell controller combined with Indilinx firmware. Regardless of whether it's due to Marvell's hardware or the software by Indilinx, or perhaps a combination of both, OCZ has managed to squeeze a lot more performance from the new design compared to the Indilinx SSDs mentioned above.
The fact that OCZ uses the chip in their Vertex series indicates that the company is convinced that the Indilinx controller is mature enough to play a role in the high-end segment. OCZ clearly believes in its reliability, given the five-year warranty offered with the Vertex 4. You can read rest of the OCZ Vertex 4 256GB/512GB preview on Hardware.info.