How's the career mode in this?
Very similar to FH5 and FH3 before that. Mostly focused on various events with their own mini-challenges and "stories" scattered across the map with different disciplines(ie. Open-road racing, street racing, stunts, etc..). Like doing quests for NPC's in an open-world game at icons across the map.
These "stories" are largely optional, and there are tons of other icons of stuff to do as well across the map(championships, different micro-challenges, stunts, even just basic ass single race events). Any event completion earns xp that goes into a larger pool of sorts and fill meters that new thresholds unlock more stuff and even big spectacle "boss" like events like racing against a blimp or a jet or something. Goofy fun. There is a TON to do and finishing it all will take a long ass time, but its designed to pull you in for quick bursts of fun or long sessions. It's very freeform.
The slight criticism is that taking part in these events is all that is often needed to progress. You get slight bonuses or occasionally exclusive rewards for getting first, but it is never really a requirement. Just competing, even getting dirt last, will fulfill completion and you can move on and keep progressing. Some really found that unsatisfying others adore that.
Oh and FH4 has the seasonal changes which add a unique twist to the environment and events. Like certain shortcuts may appear with snow piled up...while summer may lead to a drought and water lessens to allow more open road... I actually wish that came back.
Oh and it has weekly/monthly events in the "Forzathon" section of the menu which add exclusive rewards for doing essentially specific events and challenges on a weekly schedule. I actually really enjoy popping in to do those.