Well, it depends on a lot of things...
1. What shape is your wallpaper in? Are the seams really thick, lifting, torn, etc? If so, then no, it's not a good idea.
2. Is the paper textured? Is it a fuzzy textured paper, or just a raised texture paper? If so, can you live with the textured pattern showing? Because is you already hate the texture pattern of your paper, painting it won't really make it much better and you probrably won't like it either.
3. Are you only thinking of painting over it because you think taking it off is just too much work or too expensive or too complicated? If that's the case, then it might not be a good idea to paint over it just for that reason.
(I'll give you the steps to easily remove it further on, if that's what you decide.)
4. Is your wallpaper in good shape? The seams don't show much, they aren't lifting alot and it isn't torn? It can easily be painted.
(I'll give you the steps further on about how to do it and get it right, if that's what you decide.)
5. If you're paper is textured, do you like the texture but think the color just has to go? If that's the case, then yes, once agian it can easily be painted.
6. Are you in a rental and just want to make it nicer? Do you want to sell and make a profit without investing too much time or energy? Do you just like the idea? If so, again, it can easily be done.
I've painted wallpaper many times, both in my own places and in homes I have ReDesigned or staged to sell. It's easy to do, economical and can look fantastic, provided you do it right. So here are the steps:
1. Take a really critical look at your paper? Is it in good shape? Easily solve lifting seams and corners by using normal white school glue. The best way to do it without getting any glue on the paper is to either place it in a syringe or dip a toothpick in it and lightly put the glue in place. If any glue does get on the paper, wipe it off immediately with a soft damp cloth. NOT a wet one... Wallpaper is sensitive to water so make certain it's just a damp cloth.
2. Because wallpaper is sensitive to water (it can be removed with water, but it's not the best solution), you'll need to use an oil-based primer to prepare the paper for your paint. I highly suggest either Bull's Eye 1-2-3 or Kilz primer but any oil-based primer will do. I just prefer those two. Once you have applied your primer, wait for it to completely dry. You may even want to wait an extra 6 to 8 hours, if that's not too much of a problem for you.
3. Paint away to your heart's content! You can use a latex paint now that you've sealed the paper with oil. Roll your paint on lightly, without putting too much paint on your roller, most especially if your wallpaper is textured, which will avoid drips and messy work in the seams. Remember that the darker your paint is, the more you will see any faults in the wallpaper. Let your paint dry completely.
If you decide you want to remove the paper, this is easily accomplised with the following method:
1. Get a scoring tool at your local hardware or paint and wallpaper store. It looks like a rotary pizza cutter with spikes.
2. Roll this all over your wallpaper, every which way. You don't have to use too much pressure, as the spikes are quite sharp and you don't want to make dents in your wall that you'll be stuck having to repair.
3. Using a spary bottle (an old windex bottle works well or one from the dollar store), fill it with blue car windshield washer liquid and spary this all over the wallpaper that you've scored. Wait 10 minutes. Don't skip the waiting, or you'll just be wasting your time and muscle power... go have a coffee while you wait :)
4. Spray the wallpaper a second time. Wait 5 minutes. Again, don't skip the waiting.
5. Using a scraper made for this purpose, scrape the paper off the wall. It will likely come off in big pieces.
6. If there is any sticky residue on the wall, use the liquid to wash it off with a soft, damp cloth.
So... let us know what you decide... Hope this helps.
I am my source: Diva Decors ReDesign: on a mission to help you ReDesign your space... whatever it is!