I feel like Shigatsu was a way to prove that animation is a wonderful medium. When done correctly, animation is beautiful, and can tell a story through visuals alone. A great musical score to match helps wonders, for while we can visually see a story play out on the screen, if we can't hear the story, then there's no real merit to it. Shigatsu succeeded there, and I applaud it for that, and I would love to see other studios do the same. However, what bothered me the most about it were the characters and of course the melodrama. Clichés aren't bad, per se, but when nothing "fresh" or "different" is being done to that cliché, then it's just like everything else. One of the key things I personally latch onto are the characters, and if they're well-written enough to be like real people, I grow attached to them. Of course, even if they were like real people, it doesn't mean I can automatically like them, and that can affect my own personal enjoyment. The only exception I can think of is Neon Genesis Evangelion in that while I have no real opinion on the show, I cared for none of the characters on an emotional level, yet they don't bother me--probably because we technically weren't supposed to really... attach ourselves to them. We're just observing; we can feel sorry for them, but we just can't empathize.
I honestly don't want to make this comparison out of fear I'll sound pretentious or whatnot, but the reason I really and truly love CLANNAD more over Shigatsu is because the characters were that much more real. Both series have their own melodrama (they're basically soap operas), yet I got to know the characters on a more personal level, and was able to understand their own personal demons and wanted them to succeed and live life--and when they did, I was happy for them, even if they didn't get exactly what they wanted (like they would have in another world). I feel Shigatsu struggled with that when it came to Kousei. It wasn't noticeable at first, but as the show went on, it got really, really frustrating to watch him struggle with his personal problems dealt from all the pressure his mother put on him. Yes, this happens to people, but I think it was a little too much here to the point I was ready to throw my hands up at any given time and say, "I'm done. You're hopeless." I didn't say "I'm done", but I still thought, "You're hopeless" even after he kinda-sorta got over his blockade. He really is not an interesting character past his blockade, and even the blockade had its limits. Kaori has more personality than him, and was less frustrating to watch even after we got it shoved in our faces that she was very sick. She's like a more energetic Nagisa, but I still prefer Nagisa over Kaori, not because Nagisa has qualities and traits I can connect to (that I've also seen in people I know), Kaori is like that too. I feel it's mostly because she really was able to connect with her love interest, meanwhile Kaori was pretty much lying to herself most of the time. She connected with Kousei, but that chemistry never completely clicked for me, even though it's totally there. I dunno, maybe his own issue with his near-mother complex made me think it was never going to truly work out despite her being the catalyst.
Then there's the other characters who I'm really starting to forget because... I just was never interested in those characters. Tsubaki is your typical tomboyish tsundere, Watari is the guy who's just... there, oblivious to the fact that his "girlfriend" never had feelings for him when it was so obvious. There's Kousei's aunt and niece... ehhhh... Then there's the two "rivals" and I just couldn't get into them, especially with that stupid hair of that boy's, like what's with that? It bothered me more than it should have. This kind of sounds a little petty, but supporting characters are just as important as the main characters are. They may not be the plot/story's main focus, but they do help it along while still being their own strong character. And unfortunately, Shigatsu didn't seem to want to have its supporting characters grow, it was more-or-less forced to.
I am not denying the show appealed to a lot of people, however, the characters just fell flat for me by the end. I warmed back up to Kaori with the final episode here with her posthumous letter, but not with Kousei. He's still a bland character in the end who can play his piano like he used to in the past. That's all he has to offer me. Really, at the end of the day, all I took out of the anime was that the animation and art is beautiful, one of the most beautiful I've seen in a long time, it's just that the story it's telling is a bit... thin due to characters I couldn't attach to complete with clichés that are present in other works with very little differences between them--even though CLANNAD is the exact same way yet I love that anime to death. Though it makes me wonder if I would've felt the exact same way had I not yet watched CLANNAD prior to Shigatsu... unless it was because of CLANAND that I started paying more attention to the characters in everything...