As with any car there is always horror stories.
If you get a later one, after mid 05 most of the injector issues were sorted by then and they don't have any more common injector problems than any other modern diesel.
The pump doesn't need coded tho doesn't go that often. As for the injectors you can code them yourself with F super which costs £20 and can be used for fault codes too.
My ST tdci had 113000 on it now and I changed the flywheel at around 100k.
Only other issue I have had with it is the pin sheering off the EGR valve, but 80p fixed it with a bit of silver steel dowel rod.
I used to have a tddi with 170k on it and was still fine, bit noisey but ran fine. I know my G/F's uncle bought a tddi from new and used it as a taxi up to 460,000 miles and pnly put a couple of clutches in it and replaced the electronic pump which is under car which is only £100 (failed on my one too at 120k) apparently its common to fail around 100k