The falls at Niagara are great, BUT the town is seedy down-at-heel sea side type thing. Think Blackpool without the glamour. Also, depending on the exchange rate, we found it VERY expensive compared to MI. Most things cost more than I'd expect to pay in the UK, e.g. an ice cream at Toronto zoo cost the equivalent of US $3. Also, everywhere seemed to charge extra for every little thing which I'm not used to in MI, but happens in the UK more (again - the zoo, there were extra charges for extra bits you'd want to see, rather than one ticket getting you in everywhere). It's probably quite cheap compared to NYC, but I'm used to my quiet little backwater of small town living where everything is affordable.
Didn't go to the US side so can't compare.
The town of Niagara on the Lake is far nicer, but also far more expensive.
To go to Canada you need passports (this is relatively modern and lots of Michiganders don't have passports as they used to just drive back and forth) and if you drive, you need to let your insurance know. There's some kind of letter of proof that you should have in your car which they'll send out to you. (Although we've been across for the evening and not bothered)
If you're driving, then the part of Canada you drive through has a small town called Stratford that has a Shakespeare festival each summer, where they put on lots of Gilbert & Sullivan and George Bernard Shaw (and some Shakespeare).
The towns are all called things like Windsor, Cambridge, London, Stratford etc. We spent the journey spotting British towns we'd been to.