I've had one for about a year. I like it overall, with some reservations. The controls are great, the front end* is durable, it's bright, good runtime, uses existing Stinger chargers, doesn't roll, etc. The high mode isn't as big a jump from medium as you'd think, but it does put out a lot of light. Downsides are that it feels heavier than it is and I can see the shape would be awkward for some people. The 2020's main flaw is around the tailcap. It's absolutely not waterproof and the metal body is thin and unsupported at the opening. I dropped mine and it bent the battery compartment enough they got stuck. Streamlight fixed it in a few days for free but I think that's a bad design. Despite that I get a lot of use out of it. 100 lumens for 24 hours means you can do most tasks without ever worrying about battery life. Beam is biased towards flood.
If you want a Streamlight with that UI and can live with half the runtime, they have a Strion 2020 coming out. It's the same body as existing Strions and uses a normal screw-on tailcap. Technically looks like a better light. Wouldn't be surprised if it replaced my Stinger 2020. If only they'd add a lower-low mode it'd replace my EDC as well.
One of the best features of Stinger and Strion is the cradle charging. You can swap the batteries but you don't normally have to. It's a lot more convenient than taking out batteries and throwing them in a charger every day. If you only care about USB charging a lot of cheaper Streamlights take 18650s as well.
