Opinions about buying a lens?

I have a Nikon D5100, and I've been saving up for a 50mm f/1.8 for a while now, and financial situations aren't fabulous at the moment, and it'll take me much longer than it's worth to save up for the 50mm f/1.8G that has the ability to autofocus on my entry level DSLR. I can currently afford the 50mm f/1.8D, but it can't autofocus on my camera, and the material is a little cheaper. I think I'm going to go ahead and buy it, but not without some opinions.

Are there any major disadvantages to buying this lens that overpower however many years it would take to save up for the 1.8G? Is this lens a good choice, and is having only manual focus a huge deal?

Buy the lens. The big whoop about auto-focus is that you get to shoot ten pictures without thinking, in the same time it takes some who thinks, to take one shot. Auto-anything means you're turning control of your pictures over to a machine. Slow down and think.

Keep using your fine kit lens until you can afford the one you really want.

I spent the first 25 years of my photography with manual focus cameras.
I still use a 1960's manual focus camera
I have a lens with busted autofocus that I use on manual.

There really is life without autofocus!

Here's a plan:
Buy the manual focus lens
Get lots of use out of it.
Keep saving your pennies
When you have saved enough, if you still really want the autofocus lens then sell your manual lens on Ebay and top up with your savings to buy the autofocus.

You're new at photography? Do you already have the 18-55mm? If both yes and you are already spoiled with the AF of the kit lens, don't buy a lens that doesn't AF on your camera. You won't like using it.