I liked Ui. I know many don't agree, but I was happy with Hoshizora, both overall and with the girl who won. It was clichéd as hell, sure, but instead of making me annoyed, it made me nostalgic about all the good romances I've seen/read. Never failed to make me smile. Anyway, she may not have been the main heroine in the VN, but I know for a fact that she has a route, and I don't blame the anime scriptwriter for choosing to follow one of the other routes instead of the main route. VN's are nice that way, they offer you options.
My hatred for this anime was NEVER on how they chose the heroine, it's more geared towards the storyline buildup to making the choice of heroine (Ui) which is not exactly done in a proper manner that is expected of any Visual Novel that was remade into anime is supposed to be done. Most of the hatred against choosing Ui in the forums that I previously reside in is mostly based on the fact that many of the users there have already played the Hoshizora Visual Novel itself (myself included) prior to watching the anime (Anime was aired nearly 1 year after VN Release in April 2010) and I agree with them on based on three important points:
1. The main important points that focuses on the character Nakatsugawa Ui mostly appears on the common route of the game. The only sole point that focuses on Ui in her own route consists of simply half an episode focusing on the relationship between her and her own married brother who is in Tokyo (that detail wasn't even mentioned in the anime but was a mentioned point within Ui's own route in the VN itself).
2. Plenty of storyline-based screen time was given to other heroines in the story in this order: Madoka Koumoto (around 2.5 episodes, including 2x past recollections + 1 full ep that results in NB + Miko-dance description storyline among other things); Ibuki Hinata (1.5 episodes, 1 full ep with NB + archery scenes which she is revolved upon); Hina Sakai (1.5 episodes, focusing on her trying to say sorry to Kazuma, the leaving-house scenario and tug-of-war against Taizou Sakai (which is Hina's father, not mentioned in anime but mentioned in VN)); Toudou Koyori (1 episode, focuses on Hikonan Race and Keita's recovery, mentioned on VN into Koyori's route); Toudou Tsumugi (0.5 epsiodes, mainly game center scenario); and last of all, Nakatsugawa Ui (0.5 episodes, on the Onii-chan relationship as well as his marriage which made her feel left out).
3a. VN SPOILER ALERT: Ui's storyline in the VN actually does not focus too much on the relationship between her Onii-chan's marriage, but mostly on her love for Yamabiko town, and the reluctance to see it change, and as the player ventures deeper into her route, more focus was on the part of hiding the truth from each other about Kazuma leaving the town at the end of the year due to Ayumu's worsening fever during the winter season (which weighs in on all the heroines' routes as well) that was never mentioned in detail in the anime storyline as well.
One anomaly I found concerning Madoka Koumoto's storyline was her grandfather (whose strict teachings resulted her in becoming an androphobic) was alive and kicking in the anime, but one look at the VN storyline shows that both her grandparents have already passed away many years ago prior to the current story that takes place.
The recollection that I spoke about between Madoka and Kazuma is actually an unlockable "Easter Egg" of sorts in the Visual Novel which can be accessed once the Madoka Route has been cleared once and reloaded before it can appear. Other heroines doesn't have that kind of surprise available to them.
If the anime was supposed to promote the game of sorts, I can say it has been quite a failure and a spectacular one, even worse than the Akaneiro anime done several years ago, although it may trigger most people who can get access to the VN to get it ASAP to find out the real truth behind the storyline.
Summary: The artwork, as well as the realization of the characters mostly close to the details found in the VN have largely been done doing decent justice to the original work, it's the storyline and the way it was written and played out that dragged it all down. To put it simply, it's just like building a tower without laying the important foundations to make it stand upright, and you know what happens to the tower when anyone does this.
Only Advice: Go get access to the VN itself and play through the whole storyline, and you'll see how the anime has not done the VN or Nakatsugawa Ui any storyline justice in this respect. Or get the manga version if you're lucky enough (there is also an officially-sanctioned manga version on this. 2 Volumes drawn by Kurumi Morisaki).
Eh, while you've made me slightly more interested in the VN, I'm happy enough with the anime, so I don't think I'll be reading the original work. Akane-Iro is a different case, because there the heroine I was interested in didn't get much focus. I intend to read the Akane-Iro VN one of these days.
The ball is in your court on whether to get the Hoshizora VN to read the real story. I myself aggressively pursued the VN Storyline simply because of real worry about the direction the anime storyline is heading, and was in fact proven right about the bad direction it is heading. By the way, Hoshizora VN got a full translation (in Chinese) completed for some time already, and I mostly can understand the VN storyline very well since Chinese is my second language and also self-learnt a little Japanese on the way.
More spoilers (be warned, may cause dropping lower jaws):
Hoshizora e Kakaru Hashi was also the only Visual Novel released by feng to have its own Fan Disc as well: Hoshizora e Kakaru Hashi AA (The AA in the title literally means two things: Hoshikaka After and Yamabiko Another), After features After-Stories of the original six heroines for the original Hoshizora VN (1-Chapter Valentine Afters for Ui, Ibuki and Hina; 1-Chapter Natsu-matsuri Afters for Toudou Sisters Tsumugi and Koyori; plus a 3-Chapter Special After for the real heroine Madoka Koumoto), with the addition of a Akaneiro After featuring Minato and Junichi; while Another features 4 new heroines for selection: New Original Character Seira Nanamori; returning sub-character-turned-heroine Yocchan (featured in VN but not in the anime, she is also a sub-character in Akaneiro as well); Sub-Character-turned-Heroine Senka Yorozu (you guessed it, the Lady Boss of the Yorozuyo Inn has been upgraded to heroine status in this one); and last but not least for the lolicons(?), Kasane Toudou now has her own Another chapter too! Another happens on the premise that Kazuma Hoshino didn't go out with any of the six heroines in the previous work and is set more than six months after the original story ended. AA was in fact released around 1.5 years after the release of the original.