I've been playing the leak for a bit.. some opinions, and comparisions to the (oh no not again!!) seemingly apparent nemesis of all other FPS, Q3.
First off, its a testament to Q3 that multiplayer FPS games are still being compared to it. After playing this UT leak for a bit, it seems to me that they are, in fact, trying to make this next UT lean slightly in the direction of Quake 3... I say this due to the most obvious change in how your player acts, the weapon switching. I also think that the run speed, while not as quick as Q3, IS a bit faster than UT2.
The lightning gun, is also a FAR more balanced weapon than the sniper rifle from UT. Not only do you get the trail, the reload is slower, (OR, much more like a railgun, however you want to take it). Face it... if you cry about the sniper rifle being weak now, its only because you whored the hell out of the old one. Adapt, and move on.
Rockets need to travel just a touch quicker, IMO, as well as the link gun primary fire. I wont talk about the actual balance of the weapons, as I have no hard figures, and Mr. Rein has stated that its not nearly done anyhow.
Should you download the leak? Aside from a moral standpoint on this, only if you have an open mind about what you are seeing. If you expect full polish, then dont even bother.
Other than that, wait patiently for the truly next level of immersion in a FPS.