TL;DR If you like sports or romances skip it. If you like sports and romances, read it. Romantic sports mangas are hard to find. Generally it is either a sports manga with a very mild romantic sub-plot, or a romance manga with sports as a backdrop. One of the only other mangas I have read that actually tried to combine both was Suzuka, so there will be some comparisions between the two. Story:7 The story has a good flow to it and progresses well. When the MC improves, a few times the author uses the same explanations as to why he did, so it feels like a cop-out. However,overall almost every characters improvements feel natural. This manga is the first I have ever read to blend the romance almost seamlessly. The author of Suzuka, in comparison, seemed to write two seperate mangas and tried to fit them together. In the second half of Smash! the author does create unnecessary drama when everything is going too smoothly for the romance. They also change focus onto the supporting characters when the MC resolves his romance. The ending had a few things (which are spoilers) happen, which cheapen the end, but it is a solid conclusion nonetheless.

Art:6
The art is nothing to write home for, but it is pretty good. The panel layout is nice. The action does have its intense moments and nothing stood out as poorly drawn. Almost all the characters are distinct from each other without needing an "identifier".

Character:8
I really loved some characters, and I didn't dislike any of them. However there were quite a few out of character moments from multiple characters. At some points people will say that certain characters changed, but it really doesn't read or feel that way. Also, some characters seemed created to be forgotten, even in the "main" cast.

Enjoyment:7
It doesn't have the intensity of haikyuu!, or the action of kuroko no basuke. The romance doesn't have the drama of kimi no irumachi, nor the constant cuteness of horimiya. But by combining the two it is able to constantly catch your attention, making you want to know what is coming next.

Overall:7
There will always be better things out there, but I would recommend this one without hesitation. For everything it does wrong, it does three right. I never felt like I wanted to stop reading, and a few times I couldn't wait to read what was coming next.