I’m really pleased that I bought this bench as it is very comfortable to sit on, even without a cushion. I’ve never needed a cushion, but you could maybe drape a rug over it if you wanted.  
It was a bit tricky at one stage of the assembly, but I managed and it must have taken me less than an hour, though I wasn’t rushing and that included looking for the right size of Allen key. 
We’ve had it for a couple of months, August and September, so it hasn’t seen much rain. I think it would be ok if left unprotected over the winter, but I’ve bought a cover which ties on, just in case. 
It’s a good, solid and quite heavy item, so it shouldn’t easily get blown over, even here in the North of Scotland.  We will see !