I really have not compaints at all when it comes to iphone games, since I don't even play games on my phone... I wouldn't really bother much judging if graphics are proffesionally well done or not... after all the screen is just too small for anyone to really notice those issues... my point of view over this is simple, as long as it looks good for the gamer's eye it will do the trick... if you weren't an artist, you'll all probably think this is at least an allright game, visually speaking...
Well, from my artist point of view, I think the filter was unnecessary, things could look just fine without that filter lol... I also agree with big brother, even though the gui isn't as important as an entire character sprite sheet, it still should be handled under the art team, not just having your coder take on the job, specially since it's not their strongest point like in many cases, as you can probably see in here with some of those screenshots.