Pros: Reusable, recyclable
Cons: Gets dinged up kind of easily, made from aluminum, undisclosed materials in lining
I've had my Sigg bottle for a while now. As a reusable water bottle goes, it's served me pretty well. Design wise, they have a good number of options now (with different prints too) but I have the classic design. It's fine for water and what not, but there's no way you could ever get ice in there (unless you froze some water inside of the bottle).
In terms of the health safety of the bottle...well, first it's clear the bottle is made from aluminum. There haven't been any 100% conclusions drawn between any relationship of Alzheimer's and aluminum...but I suppose if you're going to follow the precautionary principle, you might want to think twice about drinking from aluminum...although they say that the liner protects any leaching from the metal.
Okay, but now let's talk about the liner. Sigg of course insists that it's 100% safe. Third party tests do indicate that water held in the bottles has "no detectable BPA" in it (although if you get a copy-cat Chinese version...well...just don't get one of those). But....yes, there's a but.
The recipe for the liner is proprietary information and thus, they don't disclose how it's made or what's in it exactly. For a while, they were calling it "water-based epoxy resin." It appears that phrase is no longer on the Sigg website itself, but it's still in the description on Amazon. Of course, the company talks about how it exceeds FDA approval. Well, theoretically that's great. The only problem is....all canned food liners are FDA approved too and those for sure have BPA in them. So there's no telling whether or not Sigg liners are made with BPA....they might be...but theoretically they don't leach (or not enough to be detected at whatever levels they were looking for). Oh and for the older bottles...there's some question about having damaged linings leach. They say now that the formula is elastic and that new bottles are worry free.
At some point, you have to shrug and say, well...we're living in a chemical soup anyway. I guess it just depends how skeptical you want to be.
I still use my Sigg (not tons, but some). But I find myself leaning a little more towards using my stainless steel options.