You still need to change blades on an electric razor every 6 - 18 months depending on hair/use. They generally do not cut the hair cleanly so you may find a higher degree of irritation whilst you get used to it. They normally work on a mashing/tearing effect of the mechanism.
Gillette make good blades, they are usually just a bit too thin now that they will break within 2 weeks use. Mach 3 was less prone to this problem I found. Not knowledgeable about wilkinson sword, but from personal preference found it worse than gillette stuff.
If you are happy to make a bit more of a ritual/time consuming then go for safety razor types and you could save money in the long run or at least have tried and know what it is like.
I plan to go that route once I have used up all my old blades.