It could be faster than current DRAMs, because its read-out is not destructive, thus no need to write back after read. Therefore, you don't need to read sequentially to get the best performance. It should perform like SRAM.
However, the cost could be a problem. There's no mention about cost compare to current DRAMs. If its cost is too high, it would be impractical to replace DRAMs as main memory.
Another usage is mobile devices. If they use MRAM as main memory, they can go "instant on/off" to save power without additional delay.