I hope if there is any bug in the new software, it will not cause the bitcoin price to drop too much.
How much do you care/hope? Anyone with a strong desire for this fork to proceed well can help: download the Release Candidate for Bitcoin Core 0.13.0 or 0.12.2 and help test it(when they become available, shouldn't be too long now).
If you're super motivated, download the source code and compile and test the main branch of Bitcoin right now.
The mega motivated can do the former, but run it on testnet, where Segwit is currently activated. That testing is the most valuable, as it directly tests the full implications of the Segwit fork.
Happy testing everyone!