I maintain BO in a small end shop (66 users), we use BO to report on 11 apps (They provided templates for the Oracle Financials, we wrote the others) once written (about 3 days work per app) I maintain BO in about 1/2 hour a week. Users will discover new fields on Forms we have never reported on before and ask for new Definitions in BO, usually it is a one to one mapping in a database table and takes under 5 minutes. Sometimes it is a calculated field and takes twice that. Very rarely, I get involved in helping a user write a report he can't do on his own, but usually the users help each other, they know the data better.
Users always get to name fields with names that they use (different users can each have different names for the same field if they like), they are not forced to learn some programmers abreviations, users never need to worry about how to join tables, users never need to learn a database language. But they CAN do these things, BO allows you to be as naive or techie as you like.
As an I/S guy, users can only view data not alter it, I control how data is JOINed, and I can set CPU time and row count limits. I can implement as much security as I need in a simple GUI. I often make the user happy before he hangs up, how often does THAT happen now?
Users make reports fast without waiting on I/S, I/S spend so little time on support, that what support is needed can be fast. Everyone likes that part!
(If you are spearheading this from the user side, bargin with I/S that their reporting time will go WAY down, so what reporting support you DO need should be high priority. BO fails if I/S won't spend the 5 minutes RIGHT NOW to keep the user focused on his reporting needs. Even the slower tasks: adding a new table, writing a stored procedure, should be done in one business day)
I tried to remain child-like, all I acheived was childish.