I've had the phone for almost 3 weeks and the experience isn't that pleasant since I'm coming from the Galaxy S9....
Positives:
Screen = It's very good since it's an AMOLED 1080p 90hz with very good colors.
Battery = It lasts me about 2 and a half days, depending on usage, but it lasts a long time, and it also has relatively fast charging.
Speaker = Good and bassy.
Now for the major negatives... this is where it gets frustrating.
Camera = It claims to be 50mp but we all know that's a marketing scam at this price, it doesn't even look like 50mp because the photos come out blurry and full of noise... In video, it shoots 1080p at 30fps... which is ridiculous, come on Samsung... you had one job with this phone... and you give me 30fps while it supposedly has a good camera? My old S9 had a 12mp camera and took crystal clear photos and 4k 60fps videos... Even my very old Redmi Note 5A Prime shot 1080p 60fps and this one can't...
Processor = It has Mediatek, no need to say more... it's well known that generally Mediatek chips lag terribly after a few weeks or months, which is starting to happen to me. All the phones I've had with Mediatek (Sony Xperia E4, Redmi 9C, Redmi Note 9, TCL 50SE) lagged and crashed... I've personally noticed that those with Mediatek just lag, both from personal experience and from friends who have phones with these processors.
Software = Since I love OneUI which my S9 had, the A15 has very poor RAM management, meaning there are 500mb free out of the 4gb it has with only social media apps... which again the processor plays a role in this....
Fingerprint = It works whenever it feels like it, and when it doesn't feel like it, it doesn't work, that's all I'll say.
And lastly, IT DOES NOT INCLUDE A CHARGER, just so you know... it only includes a USB-C to USB-C cable.
Overall, this is my experience so far which, okay, I didn't expect anything more at this price point since I'm coming from the Galaxy S9 which I had to change due to a subsidy because its battery and speaker broke after many years.