If you intend to have more than 1 concurrent user at all, any back end will work and, personally, I would look at how much data you actually intend to keep. If your database has the potential to grow rapidly and you intend to keep historical data a more powerful back end database may be preferable (MySQL, SQL etc). If you see the possibility of more than about 3 or 4 concurrent users in the future, I would personally go with a SQL back end and use unbound forms. If you don't see that possibility then MS access is fine on it's own but I would give each user a copy of a front end rather than making them share the same front end.

I've got databases that do both, and some that mix data sources between SQL and Access tables it really depends on the nature of your data and the size and rate you expect your data to grow.

Just to give you an idea though I've written purchase order programs that have 1 or 2 concurrent users which have data for the last 8 years. The tables are solely contained in MS access and I haven't had any issues with size, corruption or anything else (3 different versions at 3 different sites)