I've had this watch for 2 weeks now, so I cannot speak for durability yet.
I like it a lot. It feels great, it's light, elegant, not too big, easy to use and it certainly does what it's supposed to. What you would expect from Suunto.
But I'm not going to talk about why you may want to buy it because if you are reading reviews on this watch is because you already want to buy it; so I will rather focus on what made me hesitate:
- Aluminium: may not be the best material for a watch. It is light, it has a nice finish, but it is a malleable metal, and it will certainly scratch quite easily. So far, I have not had any scratch, but I am being consciously careful. Plastic could be more durable, but it wont be that good looking.
- Display contrast is not great. The stock images you see are certainly edited and manipulated. It reads decently well, but depending on the angle it can become challenging. With poor light conditions, it definitively becomes challenging.
- Rubber band is good, but bulky. I owned a Suunto X-Lander, and its band was as beautiful as it was terrible. I owned both the leather band and a rubberized one. None survived decently for more than a year and a half. After that, I hed to do superglue surgery to them or just get a new one. This one seems to be more silicone than rubber. It is soft to the touch, very flexible and overall seems like it will be more durable than those of the X-Lander. My only criticism is that since it is a somehow bulky watch, I take it away every night before going to sleep, and taking it off could be easier than what it is. But I have to say that even if I'd knew this before hand, that would not have prevented me from buying this watch. I still think it is worth.
- Price. That is a big criticism I have for Suunto. You can get the exact same machine for $250 (or less) on a plastic case. Do the really need to charge you $150 more for an aluminium case? I find it abusive marketing.
Overall, if anything, I would recommend any potential buyer to just be careful with scratches if you want to keep your Core Alu Deep Black in pristine conditions. If you don't mind the girly looks of the white version, I am pretty sure it will withstand scratches much more elegantly than the black one. For the very same reasons the white iPhone 5/5s tolerates them better. Under the black finish you will find shiny aluminium. Contrast will be less significant if you get the white version, which is also less expensive and for no good reason.