Built-in satnavs are (or were) bad. Expensive to keep updated, orphaned, or capabilities exceeded. Much better to have a separate (eg my TomTom), which can be replaced when necessary. Linked through Bluetooth to my phone's data connection I get live traffic, and if/when I need to bin it I gather the new models will tell you what the price of petrol is (now garages are obliged to tell the central database what they're selling at, and no more need for the PetrolPrices app). Go for one with free lifetime map updates.
However, a friend (who sees no point in dedicated satnavs and used Waze on his phone) now uses Waze on his phone pushed through to a dashboard Car Android screen (or whatever it is). Seems to me like the best of both worlds (I find Waze' location tracking a little suspect, but there are other options such as Google).
Yes I do review the route TomTom wants to take me on – usually I know better and just want traffic warnings. On my drive to Bournemouth it wants me to go M4/A34/M3?M27 rather than A350 because that is 10 minutes slower (it thinks), but 50 miles extra (that's £10!). But then the alternative routing is without optimisations that get offered along the way only when you get near them (and some it never offers), so I beat the motorway ETA as well as the mileage.
I regularly report anomalies via the TomTom reporter website. Some time ago I realised a road was missing, I wondered why it was trying to take me the long way around and when I investigated I found the aerial photos didn't show the road because it was under trees. Another time I was somewhere I didn't know and it tried to take me through a dead end with a pedestrian walkway the only continuation.
The idiots who drive into water because they're just following the directions make me laugh, but i must confess I've done that myself without the aid of satnav – I didn't realise how deep it was going to get and only decided to back out rather late (but in time, fortunately).