In comparison to a new house things that would need upkeep or need additional spends;
Loft insulation kept up to standard, it does need renewing now and again and there's a lot of square footage in a Victorian loft.
Water tanks in loft, new builds tend to have a combined boiler rather than storing hot water in the tank (I do love warm airing cupboards though). Once you discover a dead rat in one though you'll never brush your teeth with the hot tap again.
All manner of birds, bats and beasties like wasps or bees taking up residents in the loft space.
Guttering, as the roof is so high up you can't spot the damage from leaking water until it costs ££££ to rectify. Equally the down pipes are usually metal so cost a lot to replace like with like when they rust through.
Fascias - I never knew those bits on the front of a house needed repainting and cost so much (see also how the beasties mentioned above gain access to the loft).
Roof replacing, on an older property check when this was last done and whether the supporting timbers are in good nick (see above for wood chewing wasps entering through the fascia into the loft space).
Electrics, on older properties these were run off a single ring, which is fine if you're a single elderly person who just watches tv. For a family who wants to use a tumble dryer and a PC at the same time, then putting in a fusebox and a degree of rewiring is needed.
Redecorating, my childhood bedroom took five years to decorate from its lime green wood chip and chocolate gloss woodwork glory. All needed to be stripped back to wood and plaster, re-primed and then wallpapered and painted - it was a formative experience.
Garden walls - these collapse - they collapse quicker when children play on them - they look lovely and are expense to replace like with like.
Drainage , NEVER and I mean NEVER buy a Victorian house at the bottom of a hill, Victorian sewerage systems weren't built to cope with wet wipes, tampons and all other manner of items flushed down a modern toilet. If it backs up on your property, its your problem to fix even if they aren't your wet wipes!
Box sash windows, pricey to replace - not too bad to repair but a pain to repaint. UPVC could be the old cold frame stuff that needs replacing.
Heating systems, these are usually bonkers, filled up with limescale , or old oil storage heaters which cost a bomb.
Damp course, this can breakdown over time the usual fix being injecting silicon, this costs money and a plasterer.
Removing old boilers, storage heaters, water tanks -costs a bomb.
Shape of rooms - sounds odd, but rooms are never perfectly square, floors never perfectly flat so ther e is always a table with a wobble and modern furniture like flat pack IKEA can look a bit lost in a large room.
Cleaning, lots of floorspace means lots of vacuuming, lots of fireplaces means lots of dusting and high ceilings means cobwebs you need a ladder to get to. Spring cleaning literally takes up the spring.
Curtains, nice cheap ones from Wilco? Oh no not for you my friend - you have a bay window to fill, and that means a bespoke set made up.
Diy small jobs - want to put up a shelf? Simple? Nope! You generally have no idea what your drilling into in an old house, old gas light fitting, electrical wire and water pipes all there for you to put a very expensive drill bit into (oh and you will need a good drill, older bricks are decking tough so a hairdryer drill won't cut it).
Mice, very cute, very tough to get out of the floor space, solid concrete in modern housing doesn't have this problem.
I think I've just talked myself out of liking Victorian properties 
god that was cathartic!