It’s worst. Browser incompatibilities don’t break the web, and sometimes only affect the people that want pixel perfect rendering. With Bitcoin, all the nodes have not only to implement the “abstract” protocol, but be bug compatible with the “official” node (where official is whichever has the “51%” hashing power). Any incompatibility will cause a fork eventually.
> The Bitcoin core development team has worked to limit transaction malleability. There is broad agreement in the community that this needs to be eliminated. Finding the best and most responsible solution will take time. In the meantime, users of the reference implementation do not need to be concerned. Transactions are always tracked properly by the Bitcoin-Qt/bitcoind software.
From: https://bitcoinfoundation.org/blog/?p=418
> The Bitcoin core development team has worked to limit transaction malleability. There is broad agreement in the community that this needs to be eliminated. Finding the best and most responsible solution will take time. In the meantime, users of the reference implementation do not need to be concerned. Transactions are always tracked properly by the Bitcoin-Qt/bitcoind software.