I had a really negative issue with Simple: a garnishment (wasn't my garnishment -- there's someone with my same first and last name with the same birth date who has a different middle name) that was incorrectly applied to my account. When I presented Simple (and their controlling bank) notification from the garnishing agency that they had garnished the wrong account (and deposited the check from the garnishing state's treasury back into my account), Simple's response was...to garnish my account.
Suffice to say, I went back to my neighborhood bank.
To Simple's credit: Their customer support was beyond fantastic -- they were at the mercy of their controlling bank...who was receiving the garnishment request.
When Simple switched banks last year, I received a check in the mail for $3 and change for the amount that I had left in my account after moving my direct deposits and such over. Just...a massive headache.