The problem with "big deals" is the shift in focus required to even have a shot at getting one. It's not so much "problems encountered", it's that there's no way to maintain focus or vision before or after the big deal. If your focus itself is big deals, then this doesn't apply.

But most startups have to focus on the product and that's hard to do when dealing with a large company who's priorities are generally misaligned with the broader market's values.