I liked UT in its day, but isn't TF2 the current gold-standard?
I don't :(
Actually I was a little disappointed by all the upselling when they made it free to play on Steam.
UT was "buy CD for 20 quid" and then waste 4 years of my life (and many vodka and dominos soaked attendances as Multiplay i-series events in the UK).
TF2 is a weird one. I think it's undoubtedly a 10/10 game, but all the evolution since release has made the experience a bit "bloated", to use a normal software term. It's almost as if the game has had too much support for its own good.
This feedback loop has evolved what was once billed as a "class-based team action game" to, and I quote Valve's official PR, "America's favorite war-themed hat simulator." I'm not kidding.
Sure, there's some cultural stuff that you'll have to get used to (and will become apparent) as you play more, but it's not nearly as much of a commitment as, say, WoW. A newbie (to the game, not to FPSes) can pick it up and play immediately at a fairly decent level. At the same time, there's a rich culture and stories and little things you can discover, if you care enough to spend the time finding them. If not, you can just blow some stuff up and go about your day.