Only thing I don't like about sponge filters is the bubbling at the surface and the 'spray', but at least it isn't salt spray like in a marine tank.
I took the guppy from my tank at work home for Christmas break (won't be back there til next week, so had to babysit him) and he's seeming at home in here, except my two cats have previously decided that the tank is their new water bowl and refuse to drink from their actual water bowl, and when they noticed him, they both immediately started watching him lol. They swat at him from time to time but very quickly realize OMG THERE'S WATER IN THERE and run off!