Tearing is still minor on certain tracks (common to me on Azure circuit), but performance is much better. It's locked to 60fps for the most part. Do a heavy storm race at night with 40 cars and you'll see some drops.
Comparison to Forza, well that's a loaded question. What did you like most about Forza? If you like the locked progression, grinding a grid of career races and saving to buy the best cars, customizing with crazy rims and custom liveries, perusing the auction house/storefronts, then this isn't close.
If you wished there was more a focus on motorsport, than this is right up your alley. If you enjoy race weekends with practice and qualifying sessions in dynamic weather then you're in for a treat. I got disqualified my very first race for jumping the start.
So that was an adjustment.
Personally, I prefer the physics to Forza (especially with the GT and LMP cars), I think the AI is good, and the gameplay gives experiences on console that are really remarkable sometimes, like racing at LeMans as the sun rises while a passing rain shower rumbles through.
It's not without it's faults though. The physics of the street cars still feel a bit off to me, way too twitchy and create snap oversteer/countersteer too easily, especially with a pad. The terms of the settings take some investigation, pad defaults are really rough. There are still odd glitches occasionally.
When you get everything dialed in with a pad and learn your way around the UI and what terms mean, then the game shines IMO. There are settings to customize darn near everything, it's amazing in that regard. More sims should have options like this. There are some great settings in this thread, and people are happy to share if you can't find them. Takes a while to tweak them to find what works best for you. And some car classes you may need to adjust differently.
And this'll probably get me some grief, but I'm honestly glad I don't have to deal with Forza anymore.
To me, Forza had a lot of "just pretend" that I didn't care for. The lack of motorsport/real racing features bothered me. Proper rules, flags, pit-strategy, all that. You know the arguments.
They have great licenses that they don't follow through with. American LeMans, FIA GT, Super GT, Aussie V8 all thrown together in a class, racing against each other on tracks they would never race on. Hyper street cars have no business racing in R class races either. Never in real life does an Indy car or F1 car race against LMPs at LeMans or anywhere else. These are great for hypotheticals but impossible to mimic real racing series or do a proper championship.
I never got on with boosting a street car into R class, getting a racing livery, and just pretending it's the racing version. I was never into drifting. My racing fantasy is not to take a limo or van on a track day. It's to be a GT3 driver.
And pCARS offers this perfectly. The career is just that, you're a driver for a team doing race weekends, only concerned about driving. Not running a team, managing the money or sponsorships, just driving. I know some think the career is bland and boring, but it's what I've been wanting from a race game for years.