I tend to agree with the jester. It all depends on the individual. I know many guys who are happy instructing and want to continue doing so. A larger majority want out after a few years though. I instructed at the old CAP509 level and that was on the whole enjoyable, especially training well motivated airline cadets! IR and aeros training takes the monotony out of the basic exercises, but it is still basically a job watching someone else get all the flying fun! I now fly single pilot IFR stuff and get more hands on flying than I can poke a stick at.
In the end PA38, you have to make your own decision naturally. You are still strating out, so give it a bit more time before deciding what to do, but I think if you do go for the instructor rating, you will not regret it, I do not, and I know of no instructor who does. Good Luck.