Pros: Looks like a medical
device (I'm not smoking, My doctor prescribed this). Works good. Well engineered.
Cons: Looks like a medical
device (I'm not sick....really). Disposable? (I understand the battery is not replaceable, but maybe you can send back for a replacement battery). Expensive.
If you have that kind of budget and don't mind the form factor, look at the Provari.
I don't have a Darwin, so take it for what you paid for it.