On the whole, I've been very satisfied with my recent VIA trips -- good food, comfortable enough. But it is definitely worth your while to spend the extra money for 1st class.
Toronto-Montreal, in coach -- like coach in an airplane: seat pitch and width could be better, bring your own food, etc. But the ride was alright.
Montreal-Halifax return, in first (single sleeper) -- not for the claustrophobic, as the roomette is tight for space, but everything fits in and gets the job done. Food was simple but good, though you do have to pay for it. The lounge/bar car at the back, with observation deck, is well worth a visit. Complimentary continental breakfast provided there; simple but enough if all you want is a coffee and roll etc.
Montreal-Toronto, in VIA 1 -- much better than coach in terms of room, though still 2 x 2 seating; food (free) was reminiscent of airline type, but actually very nice. Big excitement was kids throwing rocks at the train at several level crossings near Cornwall ( i think it was); at any rate, they shattered one of the windows.
two years ago:
Toronto-Winnipeg return, in Silver & Blue (first) class, in single bedroom -- again, roomette is small, but functional. All meals here are included in the first class ticket prices; the food was excellent, nothing less. Much fancier selection, too, than on the East Coast run.
All in all, well worth a try. Nice to just sit back and watch the scenery roll by. The old (50's is it?) carriages are nicely refurbished; the restaurant car with its decorated glass partitions is especially attractive. And you meet all sorts of interesting people to talk to.