I cycle a bit. I have never used Strava. I thought about seven years ago, when Google had this awesome follow me(flyby route) tracer, that was my end of needs. I used it for a few months, then was bored with it.
I've heard great things about Strava, then everyone got quiet about it...and now I'm hearing things again. One of the last things I remember reading about in the news was that some "High-Tech" Thieves were using it to track users to where they were keeping their bicycles. I wasn't excited to start using it, so I put it off.
Now I've signed up. I reset my fitbit password so I could link it. What's next? What's cool or fun to do with Strava?
Find segments on your regular routes, try to get faster on them. Compete against yourself or your friends...or your enemies! I use it to find bike friendly routes in cities I don't know. If there are a lot of users on a particular segment, it must be a good bike route.
You can put your work and home addresses in it and any other addresses that you park your bike in a "privacy zone" so that information is never shown publicly and only you will see where you end and begin your rides.
I like Strava a lot but only use it intermittently as it uses a lot of data. I wouldn't say I'm competitive but it is fun to see how you rank with others and where there is some room to improve. I have privacy settings on mine too but I do find it a bit creepy that folks could still probably get a pretty good idea of when and where you'll be based on recurring routes/commutes.
Google fit seems to track your rides automatically (well, sort of) although the data isn't as nearly in depth and you can't compare your rides with other cyclists.
Strava is a great app but when use on a smartphone, it will your battery quickly.
I used Strava for a while but switched to MapMyRide, which I'd used previously. I found that Strava did put a heavy load on the battery, and also Strava required internet access to start, tho it can be disconnected once started.
One of the cool things about Strava that many people don't know is that, with so many people using it, data is being used by municipalities to study where people are actually riding. This can influence planning for bike routes.