This bag has been excellent for the last 9 months.
I replaced a Bp2 V2 that had been through the ringer. Wanted more auxiliary storage and better water bottle pockets.
When playing double rounds on hilly championship woods courses, I don't find myself having issues with how the bag carries weight. It seems to fit me well and the back padding provides some ventilation on hot days (and comfort). I also like that the rubberized bottom goes up a bit. Keeps the bag a bit dryer if it's muddy out and feels more durable and abrasion resistant than the BP2 V2.
I like the closures and waterproof zippers - on moderate rainy days it keeps the worst of the moisture off of your discs (both the main compartment and the putter pocket).
It also holds discs.
The biggest reason why I got this bag and like it is the storage. We tend to play double rounds so to me it's valuable to be able to have the stuff I'd take on a hike such as plenty of fluids (2 bottles), snacks, Ibuprofen and such, and clothing for inclement weather and sun.
-I carry lots of snacks, extra trash bags, etc on the right side pocket. Sometimes it even gets a couple of cans of beverage. The inner top pocket is great for carrying gum and ear bud cases.
-On the left side I can fit my sun hat, wooly cap, sweater, and my raincoat for winter rounds. The internal pocket at the top gets dog poo bags, and often carries a collapsible water bowl. I was able to keep a plastic bag with extra towels in a recent rainy round in the big pocket.
-I am able to put my wallet and keys in the front zippered pocket. If I smoked I figure I could easily keep stuff for that in that pocket.
-I appreciate having dedicated phone pockets on each side - although one usually has jerky in it (you know, for emergency quick reach). Not having a phone pocket is a minus for many other bags and this has two! My Iphone 8 plus fits fine.
-I like the double insulated water bottle pockets. They feel like they will last longer and they do help to keep a can of beverage colder longer. They fit nalgenes just right.
-I keep my Quick Stick in the sleeve. I've used it for umbrellas before, and didn't really think that it carried the umbrella that well but TBH it's a big umbrella so your experience may vary.
I do wish that i could adjust the top putter pocket to be shallower, but I'm pretty sure I could just stick something down in there to stand them up like a grip bag.
Note: I do often use this with the Zuca Backpack cart - Large (depending on the course) and it fits with enough room for stuff in the big side pockets, but the water bottle pockets are not useful in the cart - need to put some on the cart itself. You can easily access the top putter pocket by lifting the seat, but I do use the zuca putter pouch for putters and phone.
I have been very happy with this bag and will probably buy a BP1 V4 or B1 V5 (assuming those will exist) when this one bites the dust.