Xur popped back up on 31 January 2020. He has an Exotic weapon that everyone who didn't unlock it yet should buy immediately. Meanwhile, the Exotic armour pieces range from mediocre to pretty much useless but it might still be worth getting them.
Xur is located on Io, Giant's Scar this week. In order to get to the Exotic vendor, you will need to land on the Giant's Scar waypoint and go straight through the giant building. After getting through it, stick to the hill on the left side and continue forward until you reach the Region Chest which is marked on your map. Both the chest and Xur are in a cave, the entrance is not hard to find and close to the map marker.
As for his offerings, Fighting Lion is a grenade launcher that is a joy to have. The item goes into the Energy weapon slot, meaning your power weapon will remain open for whatever else you might want. Maybe another grenade launcher. Not occupying the Power slot is reason enough to purchase this item as it is the only grenade launcher other than Mountaintop that is in Kinetic or Energy slots, opening you up for more build variety.
Hunters weren't quite lucky this week as they can find Lucky Pants on Xur. They are useful in certain scenarios where you might use hand cannons in both Energy and Kinetic slots as precision hits will load the holstered on with a single bullet per hit. Overall, there are better options for both PvE and PvP.
Titans will have a somewhat more useful armour piece waiting at Xur's shop though. Peregrine Greaves will cause Seismic Strike, Hammer Strike or Shield Bash to cause additional damage if used while airborne. Popping barrier while wearing these will reduce melee ability cooldown which is probably the best part of the Exotic. While it can be useful, there are better options for Titans in every activity.
Dawnblade Warlocks had better luck than Titans and Hunters this week though as Starfire Protocol will be useful for Dawnblade users. It will provide them with an additional Fusion Grenade charge for additional area control. Grenade kills will completely recharge Rifts while using this bad boy so if you're abusing them, it might help you.