As usual I will be the voice of even-handed sanity. I've had USAA for 10 years now. I would say 90% of my interactions with USAA are good. We have all our insurance through them, including my motorcycle (which they subcontract to Progressive) and our umbrella policy due to my wife's line of work.
By and large, USAA is great. Again, most experiences with them have been positive. When you deploy for a long time, they will reduce your credit card interest on request.
Downsides...
1. I have had several claims with them. Most were handled well. I did have one issue with a REALLY crappy claims agent over a stolen laptop. My brother almost got shorted $6000 when they totaled his car out, because they tried to pay him for the base model when his was the deluxe. That took awhile to put right. Their agents are by and large good, but not all is perfect.
2. For savvy investors, you'll find their brokerage to be ho hum at best. Many great fund families can't be owned through USAA. Most options cannot either. I had to set up a separate Fidelity account.
3. Lack of physical branches. 99% of the time it's no issue. Sometimes, though, you really need to be able to put in face time when something goes wrong. USAA is opening some investment centers, but that's in its infancy.
4. Be careful not to get sucked in by the "pre-approval" for an auto loan. It's nice and easy, but on the last 3 vehicles we've purchased (two cars and a motorcycle) USAA has been a whole 100 basis points higher (that's 1%) than MB Financial and other reputable lenders. For our BMW, the dealer got Bank of America down 90 points below USAA. Don't let the ease and eagerness of USAA steer you away from considering other lenders.
Just a few thoughts. Overall, though, they're still your best bet.