The 8120, when OC'd is an attractive option. But its single threaded performance is horrid, and has significant power draw issues. Its only real saving grace is that it outperfoms when all 8 cores are used, and even then, the i5 and i7's more then hold their own.
I have yet to see 4 core BD results, but expect them to be outright bad. If so, then yes, BD is a failure. If those cheaper 4 core modules are at least competitive, however, then there may yet be a spot for BD in the budget segment.