It's both. The rippling mechanism combined with the distributed order book is a great way to exchange between all kinds of currencies, which is great for Bitcoin adoption. But it's a double-edged sword because it's also great for the adoption of XRP as a rival currency. If you are sitting on thousands of BTC or if you have thousands of dollars / euros invested in high end mining rigs, then that isn't a pleasant thought. It's perfectly all right to be opposed to this, as long as you realise that you are then opposing it for personal gain. And again, that's perfectly legitimate, but it works both ways. XRP has as much of a right to compete with BTC as BTC has a right to compete with XRP.

All this talk about Ripple being a scam needs to stop however. It's immature, unprofessional and unethical. If you want to preserve your investment, work to get the synergy you can get from Ripple and work to promote the advantages Bitcoin has over Ripple and to mitigate the weaknesses it has. Help fellowtraveller to build his slighly less decentralised partially competitive and partially synergetic Ripple alternative. Unlike Ripple it's not a double-edged sword and doesn't threaten Bitcoin directly, although it would also help Ripple.