The food is bad, nobody speaks English, the cabins (even upgraded ones) are absolutely tiny - smaller than a single airline seat, no showers, it's cold, and you need to PAY for that?! Wtf.
I have done the trip around 8 years ago. Most what you said is true, its not any luxury trip as you can expect. We shared 4 person cabin with locals, for example few days with ural mountains coal miners who were drunk the whole trip. First class cabins had showers others like ours not. In summer time its hot as it can get over 40C on Siberia at summer time. We didn't ate train food instead we had our own food from Moscow. It was too dangerous to get out to buy food when the train stopped as you never knew how long its going to stay on the station. They speak mainly russian on the train some can speak few words English.
Its once a life time trip which I highly recommend.