Although not perfect, this device does what it advertises - however you have to be aware of what it can and can't do. First, it's never going to be able to respond instantly to every traffic jam, and secondly it's not going to be able to pull in a signal in a low-signal area, or inside the sealed metal box of some cars.
It connects simply, is detected quickly (but you might need to wait for a GPS signal to arrive before the TomTom software shows the interface for it) and works quite well. In the UK it tunes to Classic FM (so if you can get Classic FM along your route to work, you'll get a signal with this), but it doesn't *need* to be connected to that signal all the time. Once it's had the "green circle" once, then it'll have picked up the information for the majority of your journey - RDS updates aren't that fast, even for big incidents, so don't panic about having a strong signal all the time
Like any FM signal, it's harder for it to pick up inside the car - either lay the cable somewhere good or realise that before you start - a lot of cars have heated windscreens and that can really interfere with any signal (even the GPS signal itself) coming into the car. Around London, from inside a Ford Mondeo with heated screens, I get a full signal in most areas - the same as my radio tuning to Classic FM or any other big station - at times my radio will lose stereo signal, or switch to a nearby station, and this device works on the same principles.
It does recognise many types of incident, and the software on the TomTom allows you to route around them, but it doesn't cover minor roads or very recent incidents.
That said, it does a great job. I turn it on at the start of each day, plan my route, and it keeps me informed of any major traffic on the roads that involves (including, this winter, a lot of "Road Narrows - Burst Water Main"). It gets traffic information all day long but it's rare that you see it update except for the first time it gets a signal - that's just the way RDS works. It knows about longer-term works which even the most up-to-date TomTom maps don't (e.g. a large stretch of 50mph restrictions along the M25 which have been there for almost a year). It tells you where the traffic/congestion is and how long it'll add to your journey. The software on the TomTom does a good job of routing around the traffic, or just keeping you informed.
It's not perfect but it does exactly what these devices are supposed to do. If you need real-time, always-on, constant updates, then you need the much more expensive subscription data services for your TomTom. If you're just going to work or on holiday and want an idea if anything major has happened today that you might want to drive around, this is ideal, and it's a one-off payment with no subscription. You get what you pay for though.