No disrespect to the hard working Sleepycat fellows, but I really wish Sleepycat/Berkeley DB would provide a higher level API for simple database operations. I'm glad the fine grained API is there, but another API above that, with a reasonable set of default flags for simple synchronized open/get/put/close operations, would really help. As it is I'm about ready to can the whole thing and just install a mysqld for the job. It would be smashing the bug with a big hammer, but I'd get done faster!
The subtly shifting changes in the API with each release get me too. I suspect that is a symptom of lacking a more abstract API, it would be easier to keep that API consistent and let the changes occur underneath that.