Cyan is only really a problem for me when its actually in someone a decent duelist's hands.
When they're a noob you can just slap the F**k out of them and win, but when they know how to swingblock with it it's definitely not very balanced. It's like a decent player with Cyan can beat any pro player with yellow for example. It sort of overestimates your ability compared to others if you see what I'm saying.
Blue/staff/purple are all definitely more of a concern when it comes to dueling for me. Though from what I've heard cyan is pretty dapper in Open but i never play it so idk.
Cyan is hard to deal with if you aren't familiar with a combo meta and timing swings. Cyan/Blue will obviously receive far more complaints in this patch because since 1.4 everyone has been playing a PB-Counter meta with single swings. Now that timing is required, the faster styles will require more precise timing to beat, which most people cannot muster.
Cyan is slightly stronger than yellow, but it isn't a guaranteed win. You still need to be better than your opponent to win with cyan, or atleast your opponent needs to not know how to deal with it. I've fought a number of high level saberists who used cyan against me, and after a short time I simply adapted to their style and defeated them.
Blue, is actually somewhat difficult to deal with in the right hands (But so is any style). Fighting blue requires a bit of guessing, and extremely precise timing. However it isn't unbeatable either.
Staff is actually overpowered, and is quite lethal to any style due to the combination of speed and damage it has. It is almost as fast as cyan, and does yellow damage. The only drawback of Staff is that it has the worst range of any style in the game.
Purple is nightmarishly overpowered in the right hands. It deals insane damage, has very good range, excellent half swings, and it is rather difficult to PB purple yaws. Purple can build max ACM and begin doing insane damage off of combo-trades extremely quickly. All you need to know how to do to become nearly unbeatable with purple, is how to PB consistently, and swingblock full combos.