As far as performance goes, I'd get them to replay the song! The timing is sloppy, doesn't sound very tight at all. Drums are out of time, and the guitars aren't very tight with each other. Lay off that double bass too, this is not the kind of song for that...putting more effort/practice into his main bass drum pedal would definately help out his band a lot more.
As far as the sound goes, the drums could use some cohesiveness. Maybe bus 'em with a touch of reverb, make it sound like one instrument...that could also create an illusion that the timing is better than it is as well.
As far as arrangement...well, do they have a keyboard player? Are they that kind of band? If not, I would stick to the piano at the last chorus only. Hell, I'd keep it the way it is anyways, but I certainly wouldn't put piano all over the song if they don't have a dedicated keyboard player in the band. That being said, I think the piano sounds great!
Other than that, it sounds pretty good, just needs to be edited and mixed! Keep us posted!