OK for getting started but not a professional product
Ok, well let me start by saying that monitoring is one of the most important elements in any audio system. All the other components are judged through the monitors, so care must be taken in selecting a monitoring system that will be accurate and helpful.
I got my pair of KRK Rokit 6's about three years ago. Before that I had about 4-5 pairs of decent listening speakers but none of which were studio monitors designed specifically for manipulating audio.
It is easy to tell how cheaply these are made from the bass response. You have an aggressive, unpleasant bump above 50Hz, and virtually nothing below 50Hz. I understand that they can only go so low, but I would rather have speakers that are tight, and these are boomy.
The midrage is actually not terrible. Some folks complain about the mids the most on these speakers, that they are too forward or harsh, which is partly true, but it gives you a good window into important elements in the mix, like vocals, guitars, and pianos. It can get somewhat fatiguing, but that all depends on your monitoring level.
The high end just feels cheap. I understand that price is a limitation here, but I have used high end monitors from Genelec and Focal and Meyer, and I know beautifully high end can be presented. These KRK's do not make the cut.
If you are a bedroom producer who is just getting his first interface and DAW, these might be 100% fine for you, and will help you get up and running without breaking the bank. But I would advice potential buyers to at least consider other options (JBL, Yamaha, Event), because I feel like a more sonorous, opulent sound is possible, even in this entry level price range.