While it's awesome to see that #Matrix made it to version 1.0 with Synapse, I recommend to stay relaxed about this release.
While hanging out in Synapse Admins yesterday, I felt like the release might be a bit rushed. When you are on 0.99.2 relax and update at the end of the week. I'm sure we'll see a 1.0.1 very soon.
The most important change is the check of the S2S certificate. If you use a self signed certificate or if an Intermediate certificate is missing in your chain, your Federation is no longer working.
@jochen I'm aware of that, but it's also a problem that was highlighted 3 minor releases ago.
So that's nothing really new, just enforcing what was changed quite a while ago.
What I mean is that 1.0 with the last rc yesterday, might be a bit rushed and it would have been better to release it the day after tomorrow in order to make sure that it's reasonable stable. We waited for this release since February, two days more wouldn't have been a problem but might bring up some issues to fix.