Good point Dreamweaver. I also recommend it as it will:
1. Allow more users to connect without as much slow down (it will still slow down the more users that have connected, but it won't be AS pronounced as them all doing it directly).
2. With multiple users, if only one manages to set their default to "Open Exclusive" - bang there you go, no other users will get in if they open it first. But with a split system you don't experience that happening (unless they open the backed directly).
3. With Forms, Reports, Macros, and VB Modules in the same database as your data you run a higher risk of corruption. Each of those objects present their own set of potential corruption possibilities and if just one thing happens - BOOM! You can lose all of your data, as well as your user interfacing. With a FE/BE split, AND with each user having their own copy of the frontend (which I highly encourage), if one user's FE goes bad, it won't likely affect the other users at all and you can just replace theirs with a copy.
4. When connected via a network, Access can be kind of touchy. It can get corrupted by a network interruption/disconnection if the database is still opened and connected to by a user. This can happen, even with the briefest interruption and if you have only one MDB file that users are connecting to, then a slight "hiccup" on the network to one user can affect all users as it can corrupt the database and you just lost everything. When using a FE/BE situation, the corruption is less likely to occur in the BE as the things that most often get corrupted are forms, reports, macros, and VB code.
Those are a few of my reasons for going with a FE/BE situation. And, as we all SHOULD know, BACKUP, BACKUP, BACKUP. Make sure you have good backups occuring of your BE and always keep a good backup of your most recent FE.