They are honestly looking amateurish. The first one looks really awkward because there's just one picture which does not even try and blend with the t-shirt. The second one tries to fade better, but you can clearly see the edge of where it fades out. I'd fade out the GBP sign slightly and remove the stroke and perhaps replace it with a very slight black outer glow just so it is clear what the text is saying without it looking clear it is there. I'm sorry to be harsh, but the other redbubble threads try and look somewhat nice looking for others and "official" looking (I use that term loosely as there are no real official shirt designs, but you get the idea of it looking professional).
I am pretty bad at PS compared to the other people with threads like this, so it would seem worse in comparison. Also I don't exactly plan on selling any of the shirts, as the ideas behind them are awful and the execution was even worse. I just did it out of boredom.
I have added some more Shirts and Posters, check 'em out.
I really want the guitar hero one. Where I can buy it?