pay. there are no advancement opportunities. you are either stuck in the same position or shifted sideways. raises are 'merit based' but are likely based on a opinion formed about you the day you were hired.
There is a weird vibe to the 'front office' that customers will complain about and if you have to go up their it feels like a morgue that you didn't have permission to visit.
Most employees end up discouraged. Some of that is due to employees that are detrimental to be company being retained while more skilled workers seem to find an escape hatch.
from a customer stand point--orders tend to run behind because of poor material ordering and poor communication structure. There is no quality assurance so there's a chance you might wait 30 days and get a misspelled sign--they'll fix it in a couple of days. And don't feel bad, as mentioned in the pros, no one will lose their job if something is wrong.
Tons of miscommunication. They try to have their own language on work orders most of us can't decipher because we don't know what any of the codes mean because there is no training...just learn by making mistakes...mistakes that'll probably be caught by a customer first.
Be careful about promises made during hiring or even what position you are hired for... they'll put you where they want despite your skill set.