Hiya, Findoku. Just so you know, I just edited your post including the CORRECT URL's to the images you intended to include in it - it seems like you had included the URL's to the pages where your images are displayed on ImageShack, thus resulting in them not showing up when put inbetween the image tags... all I did was replace the incorrect URL's with the actual addresses of them.
Anyway, this doesn't look bad at all, actually. It kind of reminds me of the original SMW, which isn't bad thing at all. The plot, however, sounds just a bit too generic to me... I reckon it would be nice if you could give it some more twists.
Now, onto the level screens you showcased. Level #01 looks like a generic first level to me, with lots of linearity, not much elevation, pipes and blocks along the way and such... most of us are a bit fed up with things like this, so I think it would be nice if you could edit your first level a little bit for it to look less like just another generic first level. Aside from this factor, there is also this one thing that bugs me in that screenshot taken from it; the huge amount of cement blocks that are used in that area. I personally am not really fond of INTENSE use of cement blocks in levels, so that obviously doesn't please me really much... because of this, I suggest you replace most of those cement blocks with actual ground tiles. Of course, the hack's yours, so do whatever you want...
I just think that, when people avoid putting so many cement blocks in their levels, they turn out even more pleasant than if they had LOTS and LOTS of cement blocks throughout 'em.
The first screen you showed off of level #04 seems a bit too empty (therefore, some decorations scattered around here and there would be nice), and it also seems like you missed a "be" right before the word "activated", didn't you? Heh, just add such word in your message and you are golden.
So. Your levels, in general, despite looking rid of cutoffness/glitches/major bugs, actually look a tad too straightforward and... kind of plain. It would be a plus if you could add some more elevations throughout 'em, as well as some more decorations, and perhaps even alternate paths, huh? Some of them, such as the lava section of level #04, as well as level #03, kind of remind me of some levels included in the original game... therefore, it would be nice if you could change the layout of such levels a bit.
All in all, not bad. As I said, your levels just need some more work, the plot could have more twists and stuff, etc. Give your levels some more ulinearity, decorations, and add some more uniqueness to the plot, and you have a rather interesting hack on your hands!