I don't have too many complaints with either the iPhone XS or the iPhone XS Max.
My biggest, though, is that while Apple supports faster charging, the charger in the box is insanely slow. With most Android phones, I can plug in my phone, take a shower and know that I have enough battery to get me several more hours of battery life. With the iPhone XS and iPhone XS, unless I use a bigger charger like the one included with the iPad, I don't get that same experience.
Apple told me that lots of its customers actually prefer the tiny charger to larger ones, since it's so compact and can be carried anywhere. I'd much rather have a bulky charger that juices the phone up quicker. Still, the convenience of something like a wireless charging pad is also a nice benefit.
The phones can also be awfully expensive if you want a lot of storage. The 512GB iPhone XS Max, which I had my eye on, costs more than $1,400. I just can't swallow spending that much money, so I went with the slightly more affordable 256GB model for $1,249 when I ordered my own earlier this week.
If price is a concern to you, then you really should wait to see what the iPhone XR is like. I only had a chance to spend a few minutes with it after Apple's keynote, but it has the same processor and seems to still have a really good camera, just without things like the hardware zoom lens. It starts at $749, comes in five colors and has a 6.1-inch screen that's larger than the iPhone XS. It's an LCD display, like the iPhone 8 and earlier, which is still fine but just not as good at showing colors and dynamic range as an OLED screen.