In the 1970s and 80s it was popular in the UK to Artex ceilings and sometimes walls to create decorative patterns. But many years later it hs fallen out of favour for a number of reasons. The problem with Artex at that point in time was that it often contained Asbestos and if it did get damaged it was impossible to repair. By today's standards it tends to look dated although fashions sometimes come full circle.
Should I remove the Artex?
Before you decide to remove any Artex it's important to work out if it has Asbestos in it - generally Artex done this century is safe, but Artex done in the previous century should be treated as potentially having Asbestos. To find out whether or not the Artex has Asbestos you can either find an Asbestos expert or use a testing kit provided by a companies such as this one.
Having Asbestos in an Artexed wall/ceiling is not in itself a health risk unless the surface is tampered with - so generally speaking it should be fine to leave it alone. However if you want to remove it then you should bring in Asbestos removal experts as removing it yourself will be a major health risk not only when you remove the Artex, but further down the line the fibres could still be present in your home.
If the Artex has no Asbestos then you are safe to remove the Artex. If it's on plasterboard then it's a case of removing the plasterboard and putting new plasterboard in then deciding what you want to do after that. Or on other surfaces you can use a chemical or a steamer to scrape off the Artex.
Plastering over Artex
This is a good option if the Artex has Asbestos, although there are some caveats to bear in mind. When plastering over Artex many plasterers will prepare the Artex for plastering by scraping the Artex so that all of the ridges have the points removed. The reason for this is that the ridges are uneven and have the potential to show through the new layers of plaster. But if the Artex has Asbestos in the this should not be done as the action of scraping will release Asbestos fibres into the air. So - yes you can get Artex with Asbestos plastered over but it must be treated with caution and there is a possibility that the pattern will show through the plaster. If the Artex has had many layers of thick paint put on it over the years then plastering may not be the best option as there is no telling if the paint will come away with the weight of the plaster.
Final thoughts
If the Artex has no Asbestos in then removing the Artex is best - you may need to plaster/plasterboard again but the end result is a guaranteed smooth surface.
In an ideal world there would be no Asbestos and all of it would be removed, however removing it is in itself a risk - personally in my house I've gone with a compromise and plastered over some Artexed ceilings, but others were ripped down by Asbestos removal experts. However if the Artex has Asbestos in then it really down to your budget and what you feel you can live with - whatever you do it's best not to tackle the problem yourself.