Adrian, the Droid Eris (make sure you say Eris or people automatically assume your talking Motorola droid in an Eris forum) has not been OTA to 2.1, so you're not missing anything.
From what I understand, there's a few different versions of leaks out there. 2.1 V1 which is or can be rooted, 2.1 V2 which is not rooted and I think a root of 1.5. Probably more, but that's what I've seen.
On another forum right now, there's a frenzy because someone is saying that they have downgraded the leaked 2.1 V2 back to 1.5 which hasn't been accomplished up to this point. I would look for 2.1 root threads here and on a couple other forums to find out the steps needed to do it, I myself have not. I do, however, have the 2.1 V2 and have had very few problems with it.
Some people hate the 2.1 V2, so do a little research and you'll be able to make an educated decision as to which one you want.