Same. I've heard good and bad and I was aware he wasn't exactly well-liked as a writer by an indiscernible amount of people, but I didn't have an opinion on him myself because I never read anything by him (I did think people seemed overly harsh)
My first real exposure was the JL-JLD crossover and I went in, open-minded and even thinking Bendis was getting a lot of undue hate.
Well, the crossover was bad.
Characters
Some characters were out-of-character (I don't know the JL characters) and had the same voice; on one memorable panel, Doctor Fate uses British slang like John Constantine which actually made me think the latter was impersonating him for the sake of a plan (nope, it was just bad writing)
Fights
The fights were boring both in action and in visuals. Everybody's magic looks the same except it's a different color to help you tell the magic apart during fights. I'm not even exaggerating. Oh, and the big bad is a lord of chaos who is supposedly the biggest and baddest lord of chaos - yeah, her magic is exactly like that, too.
If you're a JLD fan, it gets worse because the magic fights were a spectacle. and Xanados comes off as even more unimpressive because the eldritch villains in that series weren't boring to look at. The lord of chaos Mordru. and The Upside Down Man.
The story
It feels like nothing really happened and definitely nothing to make me actually feel the stakes involved and the weight of the lord of chaos (the story really wants to tell you how big and bad and powerful Xanados is and how she is the lord of chaos)
The story got so many things wrong, that I started to wonder what the point of making a crossover with the JLD even was if they don't bother to get anything right. I'm not putting this squarely on Bendis because editors should have stepped in to do quality control, but it was clear he hadn't bothered to do the research and I know because I can tell, by some of the things he got wrong, where he likely got his information from. It's led me to believe that the reason he got some things right in his Doctor Fate-Superman crossover was because of the editors or someone else.
Oh, and because the DC keeps doing it, I'm going to keep pointing it out: they can't get Doctor Fate's costume right and it's completely inexcusable the way it keeps happening. At one point during the second issue of the crossover, they confuse Doctor Fate's helmet with the Legionnaire Doctor Fate's helmet. Is character sheets just not a thing in the comicbook industry?