I'll admit, the battery cover slid off on me when I put it in my pocket and tried pulling out my phone in my car. It rubbed up against the jean material and slid the cover back. It wasn't day ending and it made me realize I should probably give in and by those ever needed bigger waistline pants (and give up my 34" days)... but it slid back on easily enough.
They could have put some kind of latch on it, but like I said... not a deal breaker IMHO. The phone is great! (as you can attest)