Needed Change of Pace
I've liked the Forza titles thus far, but to ignore that they needed some changes was to be blind to reality. Many, many races on the same tracks over and over becomes hard to miss over the years. It's doubly rough when one of the main tracks, such as Nurburgring, is one you really do not much care for. When I first learned of Horizon's intention to become an open world racer, ala Burnout Paradise, I had doubts. But the minds who were not behind the Forza series to date put them all to rest with the best Forza title to date.
Even though the game world is far smaller, the whole game seems more alive. There are several times fewer races, but the races are more enjoyable and the tracks avoid a deja vu feeling appreciably. The non-race aspects of the game are a lot of fun. Levelling up your notoriety makes the times when you're not racing enjoyable and useful. The PR stunts serve a needed purpose (to cheapen fast travel) and give you opportunities to try things you might not try otherwise.
The creators realized that a little simplification would be a great idea. There is a lot less customization, but the main series' obsession is one I can appreciate, but not one that ever scratched an itch I had. The design tools for cars is still there, but far less tuning. They even cut down the number of cars by a major margin --- but who, honestly, was going to drive all of the cars in, say, Forza 4? Or even 1/4 of them? Most find the 10 or so that work for them the best and stick with them religiously.
The races are fun and marginally chaotic events. The AI is clever and willing to be dirty if needed. The rally races are incredibly fun and make one long for the DIRT series before it jumped the shark. There is not a fault that really exists in the game. It is many hours shorter, but it is a more compact and fun experience. 100 hours of fun and tedium is less fun than a solid 30 hour experience without the grinding that was so painfully apparent in Forza 3 and 4 (try and complete all of the World Tour events in less than 150 hours).
In a year with good open world racers, this is a better game than Need For Speed Most Wanted (which I liked a lot). It's not at the level of Burnout Paradise, but it shows a good way for the Forza series to continue to grow. Making the game more than just races was one of the best ideas this series has had and one I sincerely hope they continue and explore in the next generation.