Pros
At the time, unmatched creative depending on team. Plenty of kind folks, most of which I gather are no longer there. Opportunity to work on bigger briefs, straddle new accounts, etc. based on your level on ambition. Pave your own way.
Cons
Many. Frozen promo cycles even after being formally recommended. No merit increase after year one. CCO at the time ignored internal issues and instead continually offered up the proverbial Kool-Aid. Long hours, like getting teams messages/requests at 10pm for a morning deadline. Plenty of ego and pressure to go around (depending on your team).