Edit: Bought Ledger Nano S directly from the Ledger site yesterday! Free shipping to Canada, it cost me little over $120. Cheaper than from Craigslist and Amazon and since its from the original manufacturer, far less reason to worry about tampering.
theyre pretty good. i have both the nano s and a trezor.
when you initially set it up and write down the seed words let it generate a btc (or whatever) addy and copy the addy down somewhere. then wipe it (enter the pin wrong 4 times) and restore with the seed. again generate the coin addy and make sure its the same addy you initially got from it. if it matches, youre good to go, start loading coins into it. no match, start from scratch, something went wrong.
its a PITA restoring from the seed on a nano s but believe me the piece of mind
knowing your seed restores correctly is worth it.
do
not keep the seed in electronic format (picture, pdf, txt whatever). yeah there are various fairly secure ways but much safer to go paper or carved or engraved and such only. use waterproof ink if you go that route. the seed is the most important thing, you can lose the nano but the seed works on any bip38 (39?) wallet. if anyone gets seed and any passphrase they have your coins. so it needs to be secure from others. make multiple copies and secure them well (bank deposit box, safe, buried, whatever).
and make a passphrase, its like a 25th word.
do not keep the passphrase with the seed. that way if someone gets your seed somehow they still cant get your coins. btw passphrase is not the same as the pin it wants you to generate.
sorry if you already know all this stuff. ive heard of folks who messed up and lost coins. not the nanos fault, operator error. so figured id post it.