I'm not sure how the expense compares, but I don't like wallpaper that much myself. You have to take it off to put more on, whereas with paint you just go right over the top when you want to freshen up a room.
I do like some of the funky patterns you can get with wallpaper but I've never wallpapered a room so I can't compare how much work it takes. It looks a bit dodgy if it's been up a long time and started to come up at the joins, but then paint doesn't look it's best after a few years either.
I have hung many rolls over the years, and it really has a purpose.If one has a old house, and can not replace the walls...or painting would not look great, due to uneven surface's...then wallpaper is a better option.
I would never wallpaper in a new home, or one that has nice straight even walls.
Wallpaper is 'dating'.By that I mean....it really has had it's day for home decorating...except in certain homes as I have just pointed out.
It can hide a multitude of sin, but you can't rush the job...and you always need to download off the Internet advice 'how' to hang it.
Countries like England will always use it.
It is not cheap to buy, and then you have to buy all the other gear...to hang it and glues ect.In time...one could get quite sick and tired of looking at it too.
With painted Walls they are easy to change, if you want too.
Practical = Paint Economical=Paint
You could also after painting add a " Decor-Sticker"....if you want to give the room a lift! You can buy them on eBay or look into a Google site.
Easy to put on, nothing needed...and! they come straight off.You can get plenty of different designs too.Not even expensive.
Have a look at the pic I have added with this answer, to give you an idea.
Make sure if you are painting to buy a GOOD paint roller, the cheap ones are not even worth the time, they leave a awful finish to the wall that has been painted.
You asked the right person! I have a house with 16 y.o. wallpaper on the walls which looks drab and faded. The wallpaper I discovered was put on with superglue - leastways that's what it must be as the only way to get it off the walls is wetting it and using a scraper at the rate of about one square foot per half hour. The walls now have to be skimmed and sanded back. I hate wallpaper and curses on the building company which put it on! Paint is the best way - if it needs re-doing it doesn't take long and gives the whole place a lift. And yes I have tried a steamer and it doesn't work (sigh).
To Pfuit...if the wallpaper is that well stuck...just leave it on. Just clean up the join lines...remove flaking paper etc, skim wall where required and paint over wallpaper. Looks fantastic especially if there is a pattern pressed into the paper. Keep in mind that plasterboard is sandwich between paper. I have done this many times with the oldest application 20 years ago and I can tell you it looks good still.