When I attempted to use /effect to buff myself up to test the snapshot features, I used the following command to speed myself up:
/effect Jynks 1 100000 1 true
and the same for other effects such as Resistance, Jump Boost, Haste etc.

What I expected to happen was for the potion to apply happily without the particle effects getting in my way, so I could just take a look at the new End structures etc.

What actually happened was that the particle effects were still visible around me, but changed from a white colour normally present form a Speed potion, to a darker blue colour.

Steps to Reproduce:
1. Create a Single Player world with Cheats enabled, or join a server running the snapshot; as long as you have operator status, it doesn't matter.
2. Attempt to use the /effect command for any potion, but use the "true" argument to hide the particles.
3. Observe how the particles are still visible, but in a changed colour.