Bought it the other day when it was on sale on steam and it seems that every time I play the damn thing, it has to update afterwards. I downloaded it and it didn't work, I'm guessing because the download got interrupted twice by the system going to sleep. A bit annoying but fair enough, these things happen.
I finally finish the download and re-download of the corrupted bits and then it won't work so I do the language change trick which uses up 3 more gig but then the game works. Double yew zero zero tee I say to myself and play the tutorial just to check its working and everything seems shiny. I decide to actually play it the next day and it won't work again. Reverifying the files reveals 19 corrupted ones which it has to re-get for ANOTHER gig of data (fortunately I've changed the download server to be the one from my isp so the data is now free). After that it finally works and I play the first mission. This morning I load up steam and bam, 250mb more data to download (I turned autoupdates off but that was before the last gig worth of reacquisition, it probably turned back on then)
I've wasted what must be 12-13gb on this game by now, for a game that takes up 8gb on disc thats a pretty hefty overhead.
Anyone else having this sort of issue?

Its just how Relic and THQ released the game on Steam. Even if there is only a single bit change in a file, you will have to download the whole file.
I went pretty much through the same experience, it had to download a lot of additional data. But it stopped downloading when all three games were updated to the same version, so that they would be compatible. Dunno why it keeps downloading data on your side.
The game also depends on the Relic Online crapware service or whatever that is called or do. I had trouble registering the games to my Relic account, something like wrong serial number or stuff like that. I have a Steam account and I need to make another to play my games?
Got pissed in the end, and deleted the games.

I own it on Steam too, however I had no such problems. Save for Tales of Valor content patch, where I was using skin pack, so the game has downloaded the texture/model files again (and the patch too, of course).
Sure, the chances of new patch being released are little to none, but other than that, all was ok. Even my friend, whom I have gifted it had no problems at all.

Is your COH the Anthology or just the vanilla game?
I had to download a heapload of patches if I was installing through the vanilla game. You could play without the patches in singpleplayer just fine, but if you wanted to play multiplayer with just the vanilla game you had to go through all the patching. I had to restart patching a couple of times for the big 2Gig one.
For the anthology, a patch window pops up and downloads all the requires files instead of downloading it one by one.
I'm playing the boxed version btw, have both the vanilla box and Anthology box.

Opposing Fronts has two sizeable campaigns. ToV is more focussed on the MP. I haven't really bothered with what little single player content it offers.

Hmm, should have done the research. Oh well opposing fronts will be on sale again one day I'm sure. Since I can count on one hand the number of games I play competitive multiplayer in (and aside from the finger that says "gears of war", I don't think I need any more) so ToV sounds like it'd just be something I'd never use

COH has been a pain in the @r$e regarding patches since it was released. For COH + OF I've got 17 patches totalling 2.35 gb sitting on my hard drive.
I must admit, though, the only reason I got the last few patches (to bring the game up to v2.601) was the excellent looking user created campaign Eastern Front :
http://www.moddb.com/mods/coheastern-front

Yeah. I ended up making it a point to buy a DD version of Tales of Valor just to not need to manually patch it anymore. Albeit, I have the Impulse version, so I can choose if I want to patch or not (and now that I have a 1 TB hdd, I don't need to uninstall it to make room :p).
And Tales of Valor IS mp-oriented, but it adds in three more SP campaigns that are actually very Men of War-ish. You can direct-control a few guys (who, admittedly, are ubermensches and Captain Americas) and there is much more of a focus on a few guys (while still fighting a huge battle).

Isn't there an option to turn off the updater for games on Steam?

Yes, but I have heard that Steam will still make you update if you aren't in offline mode. It just won't update while you aren't using the game.
Keep in mind this was a few months ago, and Steam could have fixed that (like they fixed offline mode).

Fixed that for you.

Bonkers!

Actually, I think that the massive downtime we had pretty much proves that offline mode works :p
Have you had a contradictory experience? i will be the first to admit I tend not to run into issues (or even try to use offline mode).

I still have issues, even when I'm online. Sometimes the UI will just not load up, the offline mode will refuse to go to online mode, but hell, I could care less.