Some of it's got the wrong timing.

When the percussion comes in, it's too fast for the melody. You should really make sure that it sounds right when you put in percussion. For example, while I may use the same plugin for every piece of mine (and yes, you're right on that part), the melody and the percussion have the same timing.

Now, aside from this little paragraph here, I've stayed on subject. I'm pretty sure you appreciate that when others do it. So do they, and so do I. I didn't rate it a four because you're an idiot or something like that (although you're not very wise), I rated it that because the piece could use some improvement.

Not to be harsh.

You need practice. Here are some advice and tips ok?

When I first started to make beats the first thing i did to try and train myself is to remake a song that i really liked. Just so that i can get to know my program and learn a little bit about how a song is put together.The original track by Dre is dope no doubt, but i dont think its a very good track to use to learn how to make your own music.

The sounds you used are pretty low quality and im assuming they are default sounds from FL studio. Im not sure i dont use FL but they sound bad. The beat itself really doesnt go well with the melody at all. Its confusing and off putting. Is this dubstep? what exactly are you going for? If you make another song there are some things you should consider:

If you are just starting the song will take a long long time and there will be a lot of things you need/should do. The song needs variety. This means more than a couple samples. more than a couple drum sounds. more than a couple beat variations, and more than a couple sections of the song like an intro, breakdown, drop, chorus, hook, ect...

Is the beat made for rapping? is it an instrumental? Is it too repetative? is it not repetative enough? These are things you should think about.

If this is just your hobby and you dont want to get that into it or don't want to dedicate that much time into perfecting your technique that's fine. I'm not assuming that you want to become the next great producer. These are just some pointers and tips to making music that people will actually listen to and maybe comment on in a positive way. Good luck.