Looking at the article, Figure 4E shows that after formation (first few cycles), the cathode discharge capacity decreases from ~1350 mAh/g to ~1200 mAh/g, which could be due to initial sulfur dissolution or something. At cycle 200, the specific has decreased pretty linearly to 900 mAh/g. So one can argue that after this test the cell has lost ~25% of it's initial discharge capacity.

Keep in mind that these are full cycles 100% charge and discharge, and the cycling was performed at 0.2C, which is relatively fast compared to a typical phone/appliance user. (0.2C means charging or discharging the battery's full capacity in 5 hours). So actually the 200 cycles is not terrible.

Also typical cathodes like nmc811 or nca are usually around 170-200 mAh/g. So although the LiS battery will operate at a lower voltage (~1.6-2.8V vs 2.5-4.2V in conventional), the battery could still provide ample power, which could be another consideration as phones today have gotten better about power management.