should I get the game with all the authentication problems?

I thought the demo was great but reading all the problems people are getting with authentication makes me think if I should get the game? Worst is to have the game and not be able to install it. Maybe I should just the demo for now and wait for the dust to hopefully settle....

If you're really patient, buy the game in Feb when the final patch is released.

I see no problems in buying it now, you may or may not immediately be able to play. If not, it won't be long before you do play.

Pay no attention to the drama queens here.

I think the problems are due to congestion - It took me around 7 attempts (over around 25 minutes during UK evening prime-time) until I successfully authenticated after buying on Steam - I just ignored the (very unhelpful) error messages I was getting (telling me I wasn't connected to the internet, which really wound me up, or telling me I needed to contact SI for a new key which was downright misleading) and kept trying until I got through.

just give it a day or 2 and you won't notice it.

Hopefully