It is not very challenging if your DIY abilities and expertise with other vehicles are enough, and as Atraudes said, you own the pretty standard tools.
The most challenging aspect, but still very worthwhile, is the "heater manifold" pipe (cross-over pipe) located at the rear of the engine.
If you own a store, go with it; it likely will not include the replacement of other associated components as previously said, however it will incur excessive costs nevertheless.
I understand that by browsing and searching through the most recent pages of articles, you should be able to locate several threads and posts that provide insights and accounts from others who have had similar experiences and what they discovered and faced along the process.