You are exempt from some aspects of the law but not the overall cost impact if you are under 50 employees.

My startup is still under 50 employees and the ACA has significantly increased our costs. We already offer generous healthcare benefits so the only thing that has changed is that we spend a lot more money under the new laws. The other option was to pass the steep cost hike on to the employees. This is not unique to my startup either.

For all the talk about how this law is supposedly great for startups, everyone I know has had the opposite experience in practice.

I think staying under 50 employees means you are exempt from being forced to offer insurance to full time employees (those with over 30 hours a week and/or salaried.) However, if you are offering health insurance - and most startups would be, then you are affected by the changes to private insurance.

Thats exactly right. ACA doesnt force you to offer insurance, but if you do your rates are likely to go up as a startup.

* If you're a startup that mostly employs 20-something males.

It's nothing to do with being a startup and everything to do with demographics.

Additionally, for really small startups that don't have a giant pile of capital or enough people for a group plan, the healthcare exchanges make insurance "possible" instead of "better hope you're married and the spouse can do family plan".

Some people may still consider twitter a "startup"

Traditionally, i was under the impression that it was a company intending to have an IPO that has yet to do so.

I'm aware that modern understandings differ.