I’ve used MSDE as my database engine for most of my contract projects. I’ve never had any issue with MSDE (at least none that could be avoided if I had been using SQL Server).

However, by using MSDE, sometimes I’ve had to deal with some customers’ objections regarding the ‘MSDE 5 concurrent users limit’. I think that none of my projects has ever hit that limit, not because the databases were used by less than five users at the same time but because that limit simply doesn’t exists. Of course there’s a limit, but not in the number of concurrent connections. MSDE will accept as many connections as SQL Server but it will add a delay processing requests if there are more than five operations waiting to be executed. Microsoft calls this ‘the workload governor’.

Here is an interesting read about the history of MSDE, the workload governor and the new SQL Server Express (found via Larkware News).

The good news is that there is no workload governor in SQL Server Express.