Here are the steps one needs to go through to actually benefit from SegWit:

• One needs a wallet or an account supporting SegWit
• One needs to generate new SegWit addresses
• One needs to receive bitcoins to the new SegWit address
• When spending those new SegWit funds, one can finally get a discount on the fee spent.

I believe it will take many weeks until laymen will experience any lower fees due to SegWit.

Devices like Trezor benefits from SegWit as the so-called quadratic hashing cost has been replaced with a linear hashing cost (meaning less CPU and memory is needed to process heavy transactions). However, bear in mind that this has only been solved for SegWit inputs, "old" funds are still as expensive as always to spend. (Bitcoin Cash has actually solved the quadratic hashing cost for all new transactions).

Then there is the mallability fix, which allows for Lightning. Remember that the advantage of Bitcoins is the network effect; the lightning network starts from scratch. I believe it will take years until Lghtning will get more useful than any other altcoin.

All in all, I'm not very much impressed with SegWit. I do believe we need SegWit2X for Bitcoin to be useful again. With the current fee levels, Bitcoin payments is only competitive to Fiat payments in some very few usecases, including bigger cross-border transactions and criminal use cases. That's not the Bitcoin I signed up for.