Comes with an App, batteries and lots of false advertising.
Actually, a lot of the false advertising comes from so called tech "journalists" who also write about the great advancements "innovations" like Solar Roadways, the Batteriser and the Fontus Bottle bring to the world. Either they are completely clueless about what they are writing about or are simply paid shills. Some articles are labeled as "paid insert" and suspiciously only have positive feedback. One might woder why that is ... But, back on topic.
A typical GPS tracker, which you would use to track your valuables, consists primarily of two things: A GPS receiver and a GSM radio. (It could also be UMTS, LTE or CDMA but for simplicitys sake we'll just call it a GSM modem). The GPS is used to figure out its current position, the GSM modem transmits it to you. Neat setup. But even with all the technological advancements over the last decades those things are still too big to put on your keychain or your dog. We're only slowly entering the age where its feasible to put those on bicycles.
So, how can we trim off some of the fat? First, let's get rid of the GPS. Cellphone towers are typically firmly fixed to the ground and have unique IDs. (Unless police forces use a Stingray...). So most of the time it's enough to just gather the IDs of the phone towers around the tracker and send those to you. And in fact many cheap "GPS" trackers you can buy from China already do this. The upside is that the devices are smaller and the batteries last longer, the downside is that you loose precision. Real GPS can have an accuracy of less than a meter, with phone-tower based location services you can get accuracy to around a city block - less in the countryside.
But still, there's the power-hungry GSM modem and the necessity for a SIM-card. Isn't there a way to get rid of that as well, and replace it with something low-power which lasts for ages on a single coin cell? Yes, there is a way. And this is exactly what TrackR is doing. It replaces GSM with Bluetooth. Bluetooth Low Energy (BLE) to be exact. And this is the problem. While BLE consumes way less power than GSM it's also way less useful in a tracker application. GSM towers are ubiquitous worldwide and you get reasonable reception almost everywhere. BLE however ... wait, what do those things even talk to?
GSM towers couldn't care less about BLE signals, and even if they would, the transmit strength of the TrackRs is way, way, too low to reach them. BLE reaches only around 30 meters (in funny units this is around 100 feet). So the TrackR talks to cellphones which then talk to cell towers or your local WiFi. But only cellphones which have the TrackR app installed! They call this "Crowd GPS". The problem is that very few people actually use this and contribute to this crowd. This means the TrackR might help you locate your keys in your house but it won't find your car unless you lost it in your garage....
So TrackR is in a bit of a chicken and egg situation. For tracking things further away than a couple of meters they need more people participating in the Crowd GPS - which isn't going to happen unless more people use the TrackR which isn't going to happen when the darn thing doesn't work right.
So - complete scam? No. There are still situations where the TrackR comes in handy. Like the feature to alert you when a TrackR goes out of the reception range of your phone. Useful to remind you to keep your wallet or your keys with you. Any Bluetooth beacon could do that for you as well but the TrackR does come in slick looking case and seems to be a reasonably well designed product. I just wish everyone would be honest about what the thing can and can't do.
Summary: In some situations a TrackR could be a useful product, just don't fall for the marketing hype around it. If you're worried about your vehicle, better use a "conventional" tracker.