It might "feel" like a bad solution not granular enough but if you actually test the implementation then locking is no longer a real concern. There are still improvements to be made and this is the first step towards that. Changing from a global to database lock required huge amounts of work which sets the foundations for the next releases with collection and document level locking.
In my experience replication has been extremely stable and reliable for several point releases so I'm not sure what problems you had.
It's not half-assed so much as a first step. 10gen have previously stated that the plan is to gradually increase the granularity or write-locks over successive releases.
Until they end up with MVCC...
I definitely won't be looking at MongoDB again until this is fixed for good, and until I know replication is more reliable. Had terrible problems that that too unfortunately.