Sonny 2 is in many ways an impressive game -- but I have to note for the sake of fairness that it's also a game of a type I do not particularly like. Others clearly do -- almost 7.5m plays on Armor Games, and over 1m on Kongregate.
Like Final Fantasy, Sonny 2 is a game based around turn-based combat with story elements between battles. The combat is, in fact, very Final Fantasy-esque; when it's the turn of your character to act, you click on the target, then select the type of attack (or buff or other effect) you want. Enemies (and, unlike Final Fantasy, friendly characters) deliver their attacks automatically, and in turn. Between levels, you may use points earned to increase stats, learn new abilities, and so on; there's also equipment to gain.
I don't mind combat systems like this in themselves; they're friendly to the twitch-impaired, and while not strategically deep, there's at least some strategy in choosing which attacks to use, and in what sequence, and in what upgrade path to choose for your character. The problem, from my perspective, is that games of this type are, in essence, movies consisting of cut scenes that are kept apart by boring, repetitive battles. Linearity = 100%, and gameplay limited.
But, of course, people love FF -- and this game -- so this has to be chalked up to a personal preference on my part, not a universal criticism of the game style.
And as for the story elements, they're remarkable polished, for a Flash game pretty much implemented by one guy: decent voice acting, nice Flash animations to advance the plot, and surprisingly good faux-orchestral musing for the combat scenes.
Not that the story is much other than the usual macho thud-and-blunder of most American videogames, but it's well done for what it is. (You're a good zombie fighting bad zombies in a post-apocalyptic world, with a casette tape that may or may not help you restore the memories you lost when you became a zombie serving as macguffin.)
So, you know: Good for what it is, and remarkably polished (and lenghty) for a Flash title. If you like games of the type, you won't be disappointed.