General overview
This is a well written, almost classic BL and coming-of-age story, which stays consistent and focused on the plot and the main characters. With good pacing for almost the entire span of the series, proper presentation of the plot and solid performances of the main couple, the story flows nicely and is easy to follow. Despite apparent cuteness and occasional comedy it deals with serious issues like family relations, character growth, following one’s dreams, realizing and expressing one’s feelings, communication, love, relationship, breakup and longing for a loved one, making choices and accepting responsibility of those choices and – in the latter part of the series – reality of becoming and being an idol. The story is accompanied by a decent soundtrack performed exclusively by cast members.

Plot & script
The main plot line revolves around Moo and Kang’s love story; the secondary plotline is about Potae’s and Payos’ situationship. The two storylines are, at times, opposites or reflections of each other (when Moo and Kang are coming closer, Potae and Payos are friendzoned; when Moo and Kang separate, Potae and Payos are frozen in a relationship limbo), which seems to be a deliberate choice of the showrunners and it works well. The script is pretty tight, with no filler nor longueur. We get a good introduction of the main couple from the very start of the series and the scene gets set for episodes 1-8, which deal with events spread over about 6 months; each episode marks a step in developing of the main couple’s story, which progresses at a steady pace. Events accelerate in ep. 9-12, which cover about 14 months of in-show time. There’s a time skip in ep. 10 of 12 months, but – contrary to horrible GMMTV fashion – we do learn (through retrospection) a lot of what happened during that time; this is what “saved” the time jump for me. It’s noteworthy that up until ep. 10 the story develops without major drama, with mere hints at potential problems and some foreshadowing of trouble to come. The writers did a good job setting up the emotional cliffhanger of the series and building up the tension. The resolutions of both the main and secondary plotlines are okay, although predictable (as this is a BL show) and a bit rushed (especially the Potae-Payos part).

Cast & performances
Keen gives the strongest and most memorable performance of the whole cast. His portrayal of Moo is very genuine, and the character itself comes across as very likeable, bold, optimistic and wholesome, relatable in his dreams and a certain (almost childish) belief that those dreams will come true. Moo’s saddest moments – and there’s plenty of them, despite of the show’s general lightheartedness – is where Keen really shines. As far as I’m concerned he’s not just a performer (like many other GMMTV employees), but an actual actor. A good singer and dancer, he’s even better at acting – he can proudly follow the likes of Fourth, Gemini, Khaotung, Mix and Nanon (to name those on GMMTV’s payroll who can actually act and sing).
Compared to Keen, Sea’s performance is almost muted – which actually fits Kang perfectly. Reserved, sometimes defensive, Kang moves at his own pace – though pretty often he feels Moo’s pull and follows him. There were several instances where Kang was opening up, coming out of his shell (and literally coming out) – and I wasn’t sure if it was just the character or the actor as well. That blinding, radiant smile, which brightened Sea’s face was far too rare… And – despite of all his apparent acting shortcomings – Sea managed to pull off some of the most emotional and intense scenes of the series; the gut-punching delivery was on point.
Opposites attract – and that rule applied beautifully to Moo and Kang; the chemistry is there from the very first scene. It’s easy to form an emotional connection with the main couple played by Keen and Sea – which can’t be said about other currently running GMMTV-made BL series. When together on screen SeaKeen are in their element – the show relies heavily on those two and they carry it with ease.
The secondary couple of Payos, played by newcomer Ashi, and Potae, played by Aun, is a mixed bag. Ashi mostly does a decent job, while Aun struggles to go beyond 2-3 poses (making fun of something or someone, crying and pouting).
Three GMMTV “veterans” were cast in supporting roles: Book as Moo’s cousin Shone, Louis as band leader Jang and Milk as Neth, Kang’s best friend and confidant. Milk does a decent job while Book and Louis give lackluster performances – and it’s not due to the script nor direction; I’d argue that both of their roles were miscast. Shone should have been played by someone like Mark Pakin, who can actually act (which Book can't) and elevate even an underwritten character (see his performance in “Only Friends”); Jang – given this character’s respect for the rules – should have been played by First.

Music
The soundtrack consists of seven songs written for the show and released by GMMTV Records: the title song “แค่ที่แกง” by Keen, “เกินกว่า Friend (Situationship)” by Ashi, “Check Me” by Louis, “พี่(อย่า)แกง (Don’t be fooled)” by Keen and Sea, “ดังกว่าเก่า (Louder)” by Keen, “ติดกลางใจ (Gump)” by Aun, Ashi, Keen and Louis and finally “สถานีที่ศูนย์ (Station No. 0)” – which is the strongest part of the soundtrack, with heartbreaking lyrics and a very good delivery by Keen.

Final thoughts
While the show had its ups and downs, SeaKeen kept going strong - "Only Boo!" is worth watching and rewatching mostly for this new ship. Hope GMMTV can appreciate this new gem it got.