Are they worth it? I am considering buying these Labels for TR Brainstorm and am interesting in hearing other users feedback on them.

 

It depends on the figure, really. I got the reprolabels set for CW Devastator and I love it. On the other hand, I've looked at their sets for masterpiece transformers and I think that most of them would make the figures look worse but that's because they already look so good.
Personally, I would look at before and after pics for the figure you want and decide which you think looks better. I also watch out for labels that cover molded detail: generally I don't like subtracting detail though sometimes you can push them down into panel lines with some kind of plastic tool or your fingernail. In cases like that or when they cover buttons or rivets, you might be able to reclaim some of that detail by heating the label briefly with a hairdryer and then pushing down on it. careful not to use too much heat or you could damage the labels.