I'm generally not much of one to complain about graphics quality. I'd like my games to run, and will make some compromises in visuals to have that happen. Where I start to get unhappy is when it becomes hard to see.
The following screenshots show the difference between Rift's high and low quality rendering scheme.
The big difference is the lighting. In the high quality image, the torch lights up the gazebo, while the low quality version just treats the torch as a shiny object. The issue is far more pronounced indoors.
Indoors, the very same scene becomes drastically darker - with lower ambient light, they're counting more on the torches actually working.
In any normal situation - wandering around town, soloing, or even fighting a rift in a full raid group, my computer runs fine with the normal setting. The place where I run into trouble is when I get near the main target of a large invasion event - in this case, with hundreds of mobs and players in the same area, the client sometimes crashes. As of this evening, Trion seems to have fixed things so that at least you don't have to wait in the queue again if this happens, but it's still a bit irritating.
The client itself isn't sure how to advise me on this dilemma. When I open the program in low quality mode, I get a warning upon login that I'm going to have reduced quality as a result. However, if an invasion crashes the client on normal quality mode, I can expect a tooltip the next time I log in suggesting that I switch down to the low quality version.
Unfortunately, you can't switch without closing and restarting the client, and you don't always know when to expect an event that will be large enough to matter, so it's a tough call. Do you want a slightly worse experience all the time to mitigate the relatively rare instance where things get out of hand? Or does dropping out at some crucial moment outweigh missing out on the game's otherwise impressive graphics and muddling around in the dark?
On the plus side, at least these issues don't crash the server. Still, it's an unfortunate kind of choice to have to make, and perhaps a big part of why developers have shied away from this kind of large scale event of late.