They will buy up and turn your acquired company into a burnt out shell of itself, replacing any genuine culture with hollow corporate values.
Colleagues I'd worked with for years were disappeared overnight and not allowed the dignity to say goodbye and we were never told, leaving us to guess if they still worked here or were just ignoring our emails.
There is only way of doing things, and that is the IRIS way. Unfortunately, the IRIS way seems to be a shambolic and reactive mess where the left hand doesn't know what the right hand is doing, arbitrary and needlessly tight deadlines, and operating under the antiquated thinking that one size fits all. Mushroom management is rife and you're just expected to go along with it with a dopey smile on your face.
Very suspect and bully-boy HR tactics and senior management is untrustworthy. While I can't say too much about this, if you go visit the reptile house at your nearest zoo, you'll get the general idea.
You will never be much more than a number on a spreadsheet. You will be mercilessly jettisoned no matter your prior contributions to the company if budget targets are in danger of not being met, or you're 'not a good fit' i.e. not a brown nosing game player who would whack kittens off the roof with a cricket bat if told by management.
Dull, corporate culture and loads of lip service about being a great place to work, but not much action.
Look at the absolute state of these 'genuine' five star reviews. They read like something a POW has been forced to write by their captor. Generously assuming they're all real, would you want to be working with colleagues like this day in and day out?
All genuine criticism is brushed under the carpet using the excuse of, 'ThIs iS a FasT MooVing PLAIce wiTH ConStant CHangE, NOt for EvEryOne'. Yeah, just like how not everyone could cut it on the Bataan Death March.
In closing, this is the close 2nd worst place I've ever worked at (first place goes to the firm that timed our toilet breaks and wrote me up for a late when a seagull did a giant whoopsie on my head while walking to work - sorry, current IRIS workers, I'm probably giving HR ideas here).