It's going to take you back to the NES era...
It's actually one of the few games that actually reminds how HARD these games were. Right now, I have completed the game in easy mode, because i wanted to check level design, before attempting anything harder. It was very well done, enemies and spikes are placed in strategic positions so that you must be 100% accurate if you don't want to die.
The graphics are classic, there's nothing more nostalgic than a pixelated character jumping over spikes and death traps, but they are extremely polished.
The music is also extremely good: the main theme was never annoying while I played, and that's something that usually happens in platformers with bad music. My favourite is probably the title theme ;)
The controls are good but not perfect, quite frankly you didn't get a 10 because of them. I'm not complaining about their responsiveness, they are all perfectly responsive, but I'm talking about a glitch that happened to me while jumping from a ladder to another (I've commented this on your website.. sorry for the double post there >_>). Anyway, I'll recap: if you are on a ladder, you instinctively keep pressing up to climb the ladder, but if you jump AND keep the up button down, you can't catch the ladder you are jumping towards. You have to release the up button while jumping, and THEN press it when you're about to reach it. This has caused me a lot of deaths. If you have ever played megaman, you'll immediately notice the difference.
Overall, it's a damn good game the veteran platformers will surely enjoy. It might not attract players which are new to the genre though, because, despite the infinite lives of the easy mode, certain parts still require quite some skill. But after all, there are plenty of easy games out there, it's fun to see at least one which breaks the habit :)