Now is a good time to get this; the price is down and the value keeps going up as more mods are produced and more players are getting online. Epic has already released a few free add-ons for it, and the UT modding community has always been pretty active in generating new content. Mods also make up for this game's greatest weakness -- the single player story.
The story has gotten hit the hardest in any reviews, and I have to say, it's pretty horrible. Story in multiplayer deathmatch games is really just a thinly veiled excuse for the action, but here it's bad enough to distract from the gameplay. The previous Unreal Tournaments had only back-story, short info-blurbs that added personality to the opponents and arenas, this one attempts to tell a campaign length single-player story.
At least they're trying? Well, they tried a little too hard to work gameplay elements into the story itself, but not hard enough; a little more time and creative effort may have produced less glaringly shoddy justifications and inconsistencies. If they really wanted us to believe in resurrecting machines, flag-critical power junctions, and armored energy spheres that can be assembled with ray guns spontaneously building vehicles from thin air, if they wanted us to believe this, they would have to do much work on the interface. Suspending disbelief in gameplay mechanics for the sake of a good game was far more acceptable when they weren't making back-breaking attempts to keep the characters, and players, conscious of them.
To be fair, the dialog and acting are no part of the flaw; the characters manage to be likable and believable in spite of the cliché revenge premise of the story and awkward patching of gameplay mechanics into sci-fi elements. Though no performances particularly stood out as spectacular, they also weren't jarringly poor.
But UT3 deserves better marks for what it does have: beautiful visuals and stunning sound, and most important, great gameplay. Considering Unreal Tournament games are really just elaborate technical demos for potential Unreal engine licensees, at least the storyline does showcase the power of Unreal's in-engine cinematics, with realistic animation and natural-looking expressions and lip-sync. If single player story is important to you, then perhaps you should wait until a third-party developer releases their own Unreal-based game.