I hope Smash Run is as fully-featured as Air Ride's City Trial, if not more so. So, like, custom rules, lots of interesting mid-game events, a ton of different and varied match types (which can also be played on their own), that sort of thing.
Maybe we just haven't seen many of them yet, but the only match types that really stand out to me thus far are the racing ones. Hopefully the majority aren't "battle with such and such modifier" because that would kinda get old.
That's my biggest concern right there. City Trial had a lot of different game modes, so much so that you're unlikely to get a standard race unless you specify it. With the E3 build all they had on display was a standard Smash, but even with the Smash direct that was mostly what they had shown.
We'll see, I guess.