SSD drives do not work in Yosemite?

Yes & No ...

The issue is not the SSD device it's self but the TRIM services people add afterwards which is a hardware device driver. If you don't install any 3rd party TRIM service you won't have a issue booting up. But... You will have no means to clean up the SSD when you throw files away (unless the SSD has it's own cleanup service built-in).

The rub here is Apple is tightening down the OS even more (which is a good thing!), but device drivers which are not signed won't load which is where the issue is here. OK, is there a way around this? Yes, but it turns off the the security service across all device drivers (not a good idea). For now you'll need to wait while the TRIM device driver is approved by Apple.

Important to note that you CAN disable KEXT-signing to enable third-party SSD TRIM. While this is undesirable and an additional security risk, it is no less secure than previous versions of the OS that didn't enforce the feature.

I wouldn't hold my breath waiting for Apple to support your third-party SSD. They are going to use this "security feature" to extract additional licensing and control over the hardware. The current Apple direction seems to be to "appliance-iffy" everything and kill the third-party accessory market even in the Macintosh space.