There is one point to be aware of which is mentioned on the official support page.
When connected directly to the smartthings hub, the Osram lightify bulbs want to act as a zigbee repeater and pass on messages for other zigbee devices on your account. Normally, that would be a good thing.
However, they appear to have the equivalent of a buffer overflow problem, and if you have a lot of traffic on your network, the lightify bulbs may accept messages to repeat but then drop them so the messages get lost. 
So this can cause some battery operated zigbee devices like motion sensors to appear to be unreachable or misbehaving when actually they are releasing their messages correctly to the network, it’s the bulbs that are dropping them.
This is only going to happen if your network is busy. If the only zigbee devices you have are bulbs, you’re probably going to be OK.
If you have a lot of other mains-powered zigbee devices which can act as alternate repeaters, such as relays, in wall outlets, pocket sockets, etc., you might be OK because those other devices might be picked as the repeaters instead. This will be particularly true if the other devices are using boosted zigbee, as on a zigbee network Signal strength is taken into account when selecting a repeater.
The problem is going to occur when you’re in the middle. Lots of battery operated zigbee devices, some Osram bulbs, but not that many mains powered repeaters that might have a stronger signal than the bulbs.
All of this is why some community members are very happy with the Osram lightify bulbs and others have removed them from the network altogether because they were losing messages from the sensors. It’s just going to come down to exactly how your own network is laid out.
Note: OSRAM LIGHTIFY bulbs have a known firmware issue that can occasionally cause them to fail as ZigBee repeaters. This can potentially cause other ZigBee devices to fail to update and/or respond.
https://support.smartthings.com/hc/en-us/articles/214191863-How-to-connect-OSRAM-LIGHTIFY-Bulbs
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