Mixed protien shakes fine but it isn't partially easy to drink out of, the sliding cap doesn't stay open so partially closes when lifting to drink which is annoying. Not sure if mine is broken or if they will all be like that. Also the sliding cap, even when fully open, gets in the way when drinking. Other positives, really easy to clean, solid bottle and water tight.

It's so good - perfect size and love the shape. The plastic is really solid and looks like frosted glass - love it!