The following cons are from engineering/eng-management prospective, may not related to other orgs:
1. Engineering talent/leadership is not top level, and if you are the top ranked engineer, you will feel a lot of push back and dragging. And great idea is not easy to spark out.
2. Mid-management is very laid back, need to be more aggressive to help the company moving to the right direction.
3. Granted, long staying people are now in mid-senior management level, but this is the problem of allowing the company to move forward. They have a lot of legacy, which *should* be fixed long ago if committing to it, but unfortunately, the safe route is always selected.
4. A lot of cost optimization can be done within the technical stack, but hard to convince people to care.
5. The technology management/development is traditional, you will see a bunch of Unix admin/DBA and ops, and handing day to day ops and also the blockers of moving fast in SOA world.
I understand a lot of companies have similar problems, probably Zillow is better than all of its peers, but given Zillow is young and want to move to next stage, then it has to do something different.