After some Halo3 online play at the weekend I'm still bad at it.
There has been much written on the Bungie.net site about the stats not updating - well it's not surprising because of the sheer amount of data collected and the weekend is always likely to be the busiest time, but it's getting frustrating along with the lag in the game. There were several times that I got the first hit in only to take one and get killed.
So I would recommend the game but as these problems persist I'm looking forward to CoD4:MW which has a November release date. Hopefully they won't be as swamped as Halo3 servers in XBL.