I just finished watching. I didn't think it was particularly great. Like, even if you take out the Death Note anime and pretend that never existed, it's still a 5/10 at best. But I will compare the two. I'll bust out something I said about FF and you can apply it to any remake or reboot ever If you don't want it to be compared then make a new IP. Or even use the Death Note lore but just have all new characters. And so to the point: Compared to the anime, it is bad and completely lacking in the nuance, drama, intrigue and powerful characters that made it so great.
My main problem with it is simply how rushed it is. You don't really get a feel for any of the characters and it doesn't feel like any of them went on any sort of journey. Certainly there was no time for back-and-forth mind games as per the anime, but even if you do pretend that doesn't exist, L miraculously figured out who Kira was in record time. There's no relationship between Light and L, and the Light - Mia romance seemed really rushed and unbelievable.
I don't want to be all negative. I do agree with LWL that the soundtrack was awesome, as were the general visuals. Willem Dafoe smurfing knocked it out of the park as Ryuk, and the rest of the actors weren't bad. The ending was also one of the better bits, pretty clever and definitely in keeping with the spirit of the original.
I should finish this off by saying if you're interested in the concept, do yourself a favour and watch the anime. I say this as someone who is not an anime fan, having only seen less than a handful of them in my life. I hope that explains just how good it is. As far as this movie goes, I've seen worse, but it's pretty forgettable. I sure as hell wanted it to be better than the anime and rooted for it precisely because I prefer live action to animation, but it was disappointing.