Well, I think too that the first posted reply is rubbish - mostly posting from hearsay, rather than from experience.
my kid - she is 11 - went through a few years (pre-K, then k and grade 1) in the US, and when moving to french switzerland she joined local public schools, quite seamlessly. Of course, she speaks french, but when we moved it was a lot less refined.
Truth is that the responsibility for education in Switzerland rests on the cantons, not on the confederation - there are large regional differences (3 languages, remember), and this is a way to keep the into account. However, if cantonal differences are easily found, standards are uphelp: 3 main education path, starting from about 12 yrs old (age of differentiation vary by canton): one is the "baccalauréat", so future university, second is "generic", so less complete but still covering most subjects but at a lesser level, third is "options", a more limited one where subjects are divided in mandatory and optional to lessen further the load - this one drives up to the "apprentissages" - so in fact to trade jobs. Bac is recognized internationally.
Note that 2 (and in case of the Bac option, 3) languages are included on top of the local one... so that most of the population can speak at least 3 languages... CM, I don't think that public schools in UK (nor elsewhere!!!) get anywhere close to that!!!
Finally, some extra-curriculum activities are included in the school year - typically ski trips. Every year, every class has a week off with school teachers in a chalet, learning some basics - my daughter this year learnt x-country ski and tried out snowboard... for a price of 50 pounds for the week to ensure that all kids get a chance at trying it. unbeatable, frankly.
Now, for the day in the life of the student:
Most kids still come home for lunch. It is a big problem for working moms (there are currently initiatives to change that). School day goes from 7h30-8h00 to 12h00, then from 13h30 to 16h30 (actual times vary depending on age, youger children start later and finish earlier). In this are included hours of gym, hours of swimming, crafts, and in the later year even basic cooking. The key subjects of the curriculum are Local language (so in our area, french), math and 1stforeign language (in our area, German, studied as early as 8 yrs old). As of next year, the 2nd language will be added (Italian or Latin), English will come later.
I would not put my kid back in international schools or in other ones... these are waaaaay better, if not perfect.