Guess i'll join the club and post my views about the recent burst of Q4 in our lives.

People are always going on about upgrading pc again for Q4 .. if you look at the maps, they are actually fairly simply with regards to geometry, and the poly-count seems low. It uses the doom3 philosophy (which I think is a great one) where detail is added using bumbmapping, other shaders, effects etc. The good thing about that, is that they can all be turned off, and once they are, you are left with something that is technologically not much more demanding than Q3. I prefer this much more over epic's philosophy, where each iteration of UT simply meant higher poly counts, with not much improvement on the engine itself.
I am certainly going to hold onto my x800 pro and xp3000, as I do not think it will be a problem running it with the details you would want to run Q4 at to stay competitive.

With regards to gameplay,
One of the most relevant introductions IMO, which has only been briefly mentioned on some sites, is the new tourney mode built into Q4 (Instanced map on a server, with more than one unrelated duel is happening on a map on a server; winners play eachother and loosers play eachother + single elimination tourney).

I mentioned it before in another thread, but I think this is a very significant feature being in it from the start, and not added later or done using a mod.

It will make duelling much more accessible, and newbies wont give up after being raped silly, because rather than being faced with rape after rape, you will be faced with opponents more suitable for your skill level after each loss (loosers play loosers). You will still play harder players, which is good because you need that too to learn, but its not gonna be rape after rape, where you are not really learning anything.

The importance of making dueling more accessible is significant, because as we all know duelling is where the big tourneys, events and money is at (based on quake3's life). So by making duelling more accessible, it will have a bigger player base, and in turn a bigger spectator base etc. All in all, it will be better for the competitive community, and hopefully there is not going to be such big divides between your average joe and the competitive gaming followers/players.