Around 24 hours or so with the S8+ and so far I'm very impressed, didn't think I'd ever leave iOS but the experiences just weren't close. Looking at and using the 7 Plus and using the S8 after and the 7 Plus just felt like a cheaper/inferior product (both matte black/jet black models). The new UI doesn't lag out of the box like my S6 did, stays out of the way for the most part. Little weird things here and there but not too far off from iOS in smoothness, we'll see what happens in a couple months. And I'd say the iris scanner works for me 80% of the time the first time. The 20% I have to try and position myself is really annoying but there's other way to unlock/secure if I get tired of it, haven't even used the fingerprint scanner but I don't have any problems reaching it. No real major complaints other Apple Music, idk if it needs to be updated or if the Android version is just shytty.
Overall I'd say it's the best phone I've ever used, I can't think of another one off top I've used that's better. It beats than the 7 Plus which is why I shipped it back to Verizon after work. Apple's got their work cut out.