I think this series started with very little expectations for most of us and I can say I was pleasantly surprised when it ended. Sure, there are many things that could have been improved:
1) Poy (playing Duen) was sure cute but he is making his debut as an actor (and only 21) and it showed... he needs a bit more acting workshops to deliver some lines more efficiently and also to cry without looking like he is laughing.
2) Cooper (playing Bohn) was fine but the plot of him getting jealous every episode was a bit annoying. Yes, it showed that even the main couple was not picture perfect but how much lack of communication do you need?!
3) I read in some blog that Ryan (playing Mek) dubbed his own lines (he is Chinese studying in Thailand) because he was not confident enough to say them during shooting. If that's the case, then kudos to him for trying but it sounded a bit odd. And if he wasn't dubbing his own lines, then it was not a very good choice of dubbing actor.
4) We saw Duen's family but then the little sister disappears after she almost drowns while visiting a market and the mother and father barely appeared in the beginning and then just don't appear anymore. Sure, we got to see a lot of development between all couples, but aside from Ram and the drama of his father cheating on his mother and his funny interactions with his younger brother, a bit more family interaction could have improved the flow of the show and the background of the characters.

The series had so many good things as well:
1) Talay (playing King) and Perth (playing Ram) were a revelation, especially Talay. Both were able to portray their characters very convincingly and showed their chemistry. Talay showed us how much future of an actor he has as this is his third show (all BL characters) but playing very different roles in all 3.
2) This show actually gave all 4 couples almost equal amount of time on-screen instead of having the main couple and the others just sprinkled every now and then (like "2gether the Series" and really most GMMTV BLs).
3) I'm glad this show didn't have the typical bitchy/screaming female trying to sabotage the couple (see Pam in "2gether the Series" or the girl from "I am Your King SS2" for some examples).
4) The story had some ups and downs but it had more believable situations (compared to becoming my fake boyfriend because you made me break up with my girlfriend like Frank and Drake in the terrible "My Tee").
5) The cast had so many changes (except for MD playing Thara) but despite that, they had great chemistry and the story was not that rushed so we could actually see good progress instead of solving everything in the last few episodes.
6) This might be unpopular among some of you but I was happy with the kiss scenes we got and glad the director didn't try to force more intimate scenes. The development of the couples was just right for what we got and more just for the sake of showing some handsome actors shirtless and kissing (like most episodes of "WhyRU" for example) would have been unnecessary. And at least we got actual kiss and not pecks or high-fives, right?

Hopefully season 2 doesn't disappoint as right now our expectations are high and we get to see some more development in all the relationships, including the "bros" Thara and Frong and maybe some drama introduced by the families. Oh and where is Cupcake (Thara's pet lizard)?!