If you mean significant in the regard that it makes a difference for the better, then yes, I vouch for Bitter Truth Aromatic bitters. I've also sampled Scrappy's Aromatic bitters. Both are superior products at a premium price (~$16 for a good sized bottle). However, the difference is not so large that it will transform a cocktail recipe that calls for Angostura. You're not missing out on much, but I think you would be pleasantly surprised.

When it comes down to it, I would be happy cutting my huge bitters collection down to Angostura, Regan's, and Peychaud's.