You do get a 25k companion award, which can be used on anyone you are traveling with. That will offset at least half the fee or more depending on how you value it. The award can also be topped up with points for a more expensive flight.Is it worth the $395 fee?
The partner award fee is also waived which will save ~$100 after a few partner award bookings.
Besides that, it's mainly for people who want to spend to earn elite status with AS.
Extra $300 for 15k pts, 25k companion award, 3 x foreign spend and waived partner award fees is definitely worth getting over the signature version. IMO