Free! is a very cute anime. The visuals are lovely and warm, fitting the lighthearted atmosphere perfectly. The music will get stuck in your head at the most random times because it's so good, however, the ending song can take a little getting used to. The characters all have their own fun traits and have more personality revealed as the series goes on. The second season is a little more serious than the first, but it is still good. Ignore all that mess about "fanservice". Yes. It can be interpreted as gay or straight. So what? Plus - it's a swimming anime, so of course there will be shirtless guys. But the males are not objectified.
Honestly - my only complaint is that Rin cries so much. It's freaking annoying. Lol. And about sports of all things.