firstly it would be unfair not to acknowledge the merits of the story, so i shall: the art is gorgeous, as per takarai rihito's usual standards, and the premise of the story exudes potential, as many have pointed out. Being a yaoi fan myself, i'll also add that her portrayal of intimate scenes leave nothing to be desired as well.
it's everything else that's lacking- there is practically no character or relationship development (alright, the latter progresses in a purely sexual nature, but is devoid of emotion). The only change we see in Shirotani is his sudden overwhelming physical lust for kurose. Psychologically, he's made no progress and still despises contact with others, even kurose; at this point, i find the constant tension between his aversion to touch and lust for kurose (the latter predictably ALWAYS WINS OUT) tiring. Emotionally, i don't detact anything remotely resembling actual affection from either of then. Shirotani's desperation for kurose's presence seems to end with his physical satiation. Kurose has got to be one of the most wooden, not to mention unbelievable characters who have dropped the l-bomb ever. Actions speak louder than words. Kurose's actions just reveal him to be callous, possibly excited at the prospect of a new sexual toy, and basically a person not to be taken past face value ever.
Others might point to the story's potential to be a 'darker' romance, but having read my fair share of those, i will point out that those Dark romances that are usually successes tend to have both characters in a couple act in morally questionable manners because they are driven by an obsessive unhealthy love for their partner- that's as simplified a plotline as you can get. But love is evident anyways, despite being in an obsessive and unhealthy form, which is more than i can say for ten count.
I feel that takarai rihito's blatant attempts to Darken the story further via the revelation of Shirotani's Dark Past further point to Ten Count's failure as a Dark story. While not pleasant, it didn't come as a shock either. I didn't react with anything other than mild disgust and also annoyance at how many pages (or was it chapters?) the whole back story seemed to span. I really don't feel like it added anything to the plot at all.
Tldr if you want something pretty with gratituous boy sex that has made an attempt to organize itself into a Deep Dark Story this is for you (but i'd say the plot is pretty thin on the ground). If you came expecting plots similar in type and or quality to the mangaka's previous works, run. If you're new to bl and this is your maiden story, you will probably worship it as the Best Story Ever right until you meet Only the Flower Knows or something.