Is it worth me buying this game?

Im a fan of manager games, only really playing LMA though.

Is it hard to get used to?

Any frustrating bugs/glitches?

Whats it like on XBL?

Any more information is appreciated.

In my opinion its by far and away the best football management game and without doubt the most realistic. If you have never played the series before, it will seem a lot more complex than LMA but brilliant if you put in the time and effort.
There are no really annoying bugs or glitches except for a slight stutter here and there.
It can be frustrating to start with but if you read through some of the guides they help a lot. The guides are normally written for the PC version (8.02) but the stats and the programming are exactly the same on the xbox 360. You can only load up 3 leagues with up to 10 divisions but that is enough as the detail is outstanding.
Most important thing i can say is give it time. I wanted to throw my copy out the window for the first few days but have really gotten into it now and its fantastic.

What are the 3 leagues i can have?

The 3 leagues that you choose is entirely up to you.