I tend to run a pretty beefy machine, so that too much hardware bit doesn't really seem to apply. I haven't seen any degradation on anything I've tried it on as of yet at max resolution. Running an r9 280 for graphics with an i7-4790k cpu atm.
As far as size goes, I've been running on 2 28s (well a 27 and a 28, now 2 28s) for years. So, while > 28 in monitors are more pricey (kind of what you'd expect, though, right?), also not really much of a factor in deciding to get a new updated 28.
60hz seems to be pretty much the standard at this time and it looks great - granted I've been running at 60hz on my previous monitors as well, so zero diff. I will say that out of the box my new monitor was config'd at 30hz (took 2 min to change up) and let me tell you - 30 mhz is god freaking awful - probably on any modern monitor but very certainly on a 4k one. Make sure w/e you get is at least able to do 60hz. Also, be wary of the dimensions when shopping. There as some monitors that are in a crazy widescreen format that's kind of off - eg like really wide and not as tall as it should be.
I can say that the image quality is great and its a night and day comparison between my old monitor and this one. Things are much more crisp... but again, you'd expect that at higher rez. Worth it? well, I mean, if you need a new monitor, sure. I like this one, to be sure. Didn't really need a 4k, but its nice.
