Anyway, my immediate first impression is that this film can certainly be compared to a mix of "Babel", "Crash" and "Lost in translation" - but the story is not fragmented as much as in "Babel" and "Crash" and you don't move back and forward in time (except for maybe a couple of scenes).
The film draws you in and cause interest from the first minute so Moodysson is certainly back to the public appeal of his first three films, even though there are few direct similarities - except for the heavy use of pop music. Soundtrack request!

The film is simply a portray of various situations and people at various stages of success, some might say it's naive or "not really about anything", but sometimes it's nice to just observe without really having a traditional storyline. I can see that the comments on imdb.com already ranges from "Fantastic movie!" to "Pointless movie" - and I guess that's the way it should be.
If you liked one or more of the above mentioned films I'm sure you'll like this one. Personally I like "Lost in translation" more than the other too so I could maybe have liked Mammoth to move even further in that direction.
Certainly the films also has a few flaws, i.e. Tom's computer game job is very vaguely described and as a software engineer myself it didn't seem totally believable that he was a "computer geek" (considering he could of course simply do some work in his hotel room instead of being bored all the time, but then again that wouldn't quite fit into the film...). The name used for a computer game and a web site Tom has started were little inventive, but that just me being nit-picky. Other than that I like that it's used real product names when making references (i.e. "Skype", "MySpace") and real screenshots of a computer (rather than a fantasy-OS used in many other films - that just looks stupid).
To continue on the technical side, this is Moodyson's first film in full cinemascope format (2.35:1) and the photography is very good as always - maybe a bit more conservative than his previous works - it certainly doesn't get in the way of the storytelling (i.e. you don't notice it). This might be explained by that cinematographer has changed since "Lilja 4-ever", it's no longer Ulf Brantås but Marcel Zyskind - while the rest of the team behind the camera is more or less the same as always.
Well, that's just my first impressions. I look forward to see the film again on Blu-ray in not too long time. If it turns up in the local cinema eventually I might watch it again there too.