No problem with them for insurance but their rates aren't the absolute cheapest. But the service is good in my experience.
Never used them for anything but a small home improvement loan, and that went ok. Their rates aren't the absolute best but it was really easy to do over the phone.
Banking... Very easy and convenient except for 2 things. First, no physical bank locations means you will always need another local bank account to do stuff that requires a teller. Second, USAA's savings account rates are absolutely horrible right now. They were much better during the boom economy, but right now ING Direct, another "online" bank, has almost double the savings account interest rates. USAA's own customer survey gives their savings accounts only 3 out of 5 stars because of the low interest rate.
Investing - Easy to do, very convenient, not quite as full-featured as maybe a schwab account would be, but USAA is very convenient.
Overall, the convenience and company quality for USAA is very good and I use them for banking, investing, and insurance. Their insurance isn't the absolute cheapest but I have not ever had them try to cheat me or raise my rates to an unexpected level.