How does Ultimate Fantastic Four compare to 616 and/or the cartoon?

I've never really been a big Fantastic Four fan. I've usually only watched it growing up when my mom did since she is really a fan of the series. I have read the first arc of Ultimate Fantastic Four and I did enjoy it but wasn't enough to go out and start collecting it. Just wasn't sure if it would really grab me. I did like the movie though.

Another reason was that Sue and Reed were in their teens and seemed to be starting a relationship. Being so used to being married for so long, I wasn't sure how I'd feel about a teen relationship verison of them. I mean if it was going to be a strong relationship with no one coming between the two of them as it grew stronger, that's great and I'm all for that. If it was going to be a relationship where Reed was always in danger of having some guy trying to take Sue away from him or her flirting with every guy that guest appeared (the cover with Ultimate Namor and Sue for example was a big turn off) and not really being into Reed isn't interesting at all.

So I guess what I'm asking is what is their relationship like? They are what in their late teens, just about to turn 20?

Not so much worried about Johnny and Ben since any changes to them I can pretty much deal I guess, same for their enemies.

With someone with limited FF knowledge apperciate and enjoy the series or will some knowledge of the 616 universe be helpfull to really make a person apperciate the changes?

Are the issues done in arcs made for TPBs? Short arcs (2 to 3 issues), long arcs ( 7 issues) or does it pretty much alternate?

How much does it cross over with the other Ultiamte titles? I know Johnny showed up in Ultimate Spider-man for two issues but that's pretty much it for Spider-man and FF interaction that I've seen in the Ultiamte Universe.

In terms of comparing it to the 616's early years. Good, bad? Really different, similar with slight changes and twist?

Anything else one can add would be great. Thanks.