I could talk about minor annoyances like the lack of coordination between teams, lack of well thought-out long term strategy and confusing processes, but there is actually one much larger problem lurking around this company that every new starter should know about before getting into this place:
That is, if you like free speech and actually making a difference instead of being a puppet, you will hate this place.
It doesn't matter how nice and helpful you are to other people and it doesn't matter how politely and constructively you disagree, you will be told to be silent. Not in these words of course, you will rather get a sh.. sandwich. They will very politely sit you down and make you go through the "Ocado Values", making you log your time and go through each minute, comparing it to the official checklist. Did you disagree with your leader's exact commands? You lack trust, which is an Ocado Value. Big mistake.
Which is ironic, given that trust is impossible in this company. They successfully created an environment where even if you have a friendly discussion in private with a teammate, whatever you said there you might hear it back later as a complaint against you. Not to your face of course. This makes everyone walk on eggshells all the time, especially people with more unstable circumstances or a family who cannot afford to lose their jobs. Which is the majority here.
On the other hand, if you don't care about things like this, you just want to sit around with a headphone, fix some bugs at a very comfortable pace and not have to have any of your own input or say about things, you basically have nothing to worry about. So it really depends on your personality.