Little Busters is an odd addition to Key's otherwise flawless lineup of works. While retaining some of Key's traditional features (bits of random magic, harem-based approach, moe female cast) the series tries a bit too hard to make itself more accessible to the general audience; in the process it loses what makes Key works so special. Perhaps I'm being too harsh on Key, perhaps I should blame J.C. Studio as KyoAni apparently doesn't own a monopoly on animating Key's works anymore. Regardless, Little Busters is a drawn out piece about friendship, and an incomplete one at that. Many of the questions introduced in Little Busters will (supposedly) be answered in the sequel, introduced in the last episode.
If you're looking for a regular group-based harem with an extra focus on moe/magic rather than fan-service, you'll find it here. If you're looking for deep character bonds or epic storytelling, you'll be disappointed here. Also, if you're a baseball/softball fanatic, this also isn't for you despite the premise of forming a baseball team.
Animation:
All of Key's previous works were blessed with vivid colors and an uncanny attention to background details. With the switch to J.C. Studio, that's no longer the case. Now I'm not saying that the animation isn't good, it just isn't what I've come to expect from Key works. As for characters, you have a huge cast consisting of mostly moe girls and a few dudes. All are easily distinguishable though facial emotions are a bit understated at times.
There is some action involving unconventional fights with random weapons (whatever is tossed in front of the fighters?) and baseball practice, but nothing truly worth of the name "action". Likewise, being a Key work, don't expect significant ecchi.
Sound:
The OP is an average light rock piece, as is the ED. The BGM consists of surprisingly few tracks; thus given the 26-ep length you're sure to start remembering some of the melodies.
The VA cast is led by Yui Horie, though she voices a dude, which I haven't heard in a while. I'm not big on the VA cast in general but Keiko Suzuki did a great job voicing the Saigusa/Futaki pair who have very different personalities. Personally, I don't think Yui Horie really fits with a guy's role. Komari's voice also started bothering me as her voice just sounds too artificial.
Story:
The Little Busters are a group of five childhood friends (four dudes and a tsundere girl). Kyousuke (oldest by one year) is in his last year of high school and decides that the Little Busters will form a baseball team. Given that a team needs nine members, it is up to protagoinist Riki to find new members for the Little Busters. This first season is about Riki's attempts to recruit new members and the mysteries surrounding most of the members.
The majority of the show follows traditional Key progression and introduces heroines (yes... Riki apparently is only able to recruit girls) one at a time. I won't reveal which of the Busters get significant exposition as some of the characters didn't (I assume that means the remaining characters will play a significant role in the sequel). Each heroine arc builds to an individual climax and resolution before progressing on to the next arc. However, this isn't a very focused show. There is a lot of filler, unnecessarily, that makes this series significantly longer than it ought to be. Progression even during the arcs can be very slow at times.
The show also suffers from an execution point of view. J.C. Studio doesn't capture the Key mood as well as KyoAni. There are serious and grave moments in Little Busters, but the severity and supernatural elements are blended with an abundance of light-hearted material; so much that the impact of the situation is greatly diminished. It's like showing a scene where someone has a mental breakdown and then following up with everyone making jokes over ramen. Perhaps this is just to cover up the fact that the supernatural moments don't really make any sense, and the director wanted to cover up the illogical parts.
Character:
Those who've read my previous reviews know that I am a big opponent of character spammage. This series is all about character spammage. From the OP onwards, you are immediately bombarded with dozens of characters and, not knowing who will be important, you try your best to catalog all of them. To your dismay, you find that a good deal of them are junk characters with little significance.
While many of the characters have cute traits, the characterization is quite shallow in general, as other recommendations have pointed out. In the end, friendship seems to be used as the key to solving everyone's problems, which I guess is why some people find this similar to Angel Beats. There are still many characters without background explication, perhaps that will be the subject of the sequel.
I also have an issue with the relative maturity of the characters. Despite supposedly being set in high school, the majority of the characters act as if they were elementary of middle school students. Perhaps I'm just getting old, but the goofy, overly-simplistic mindset of most of the characters was quite annoying for me.
Value:
In every previous Key work, there have been immense cliffhangers as a result of great storytelling and execution. This is completely missing from Little Busters. Each episode was somewhat a battle of willpower to keep going. There just wasn't anything particularly interesting- be it characters or plot progression. Like previous Key works, there is an underlying magic-based plot; however it is so thin here that it might as well not be presented.
I'm predicting that Little Busters is going to end up something like Clannad, where all the heavy, emotional content is delayed till the second season. Even if so, I'm obviously not a fan of the switch to J.C. Studio. This work shames the Key name; I'm going to treat the series as a counterfeit, it has Key elements but lacks the heart and authenticity of previous works.