I'm onto my second MK3 facelift Octavia with this engine & dsg box, my current Octavia has covered 66k up to now, no dsg or engine issues with either motors so far.
They are known for going through sparkplugs fairly quickly or within my experience, anyway. Other than that I'd have no issues with buying this engine again.
On my previous 1.5tsi dsg, I replaced the rear wiper motor & boot lock button switch (common issue), other than a recent software screen glitch that's not occurred again, they've been reliable. I also replaced a set of plugs after 10k. Both engines have ran smooth from cold & hot, until one of the plugs started to fail, it was then running lumpy for a bit without any dash lights, until I replaced it when a dash light came up with a cylinder missfire, caused by the plug breakdown.
If my current Octavia wasn't under Skoda extended warranty I'd prob have the dq200 dsg box oil replaced & the mechatronic box's oil replaced, too. Both sealed for life, but we know what that means. I bought my current Octavia from a skoda main dealer, it came with a yaers extended warranty, when that runs out I'll be taking the Skoda all in 2 year warranty out, inc servicing & breakdown cover, as it's reasonably priced. If I have my car after that I'd then prob change the gearbox oil & have the timing belt replaced, too, but as they'll all be covered under the extended warranty, I won't until then. So far I've not had any dsg related issues with either car, the 7 speed dsg box has always ran smoothly without issues.