I haven't noticed a 'mass'ive difference but hopefully it's having some benefits hard to gauge unless you meticilously measure these things which I don't I'm afraid, but no downsides so must be ok.
Adds a few percent to gains I reckon, no sides
I've used this on and off for a while. On, you for sure gain some mass. As long as you are doing everything else right of course it's not a miracle gainer. However for older trainers like myself I feel this makes a difference. It's probably healthy for you too being a concentrated extract from things like rosemary.