As Eurogamer points out, "aside from killing off access to retro games, downloadable titles and DLC, this also means that online gaming is off the table too, not to mention video streaming." Joystiq finds the Wii menu "strangely empty" and Engadget says "firing up the Wii Mini will be the real shock if you're used to the Wii," though they also point out, "for the target audience mostly just concerned with playing Super Mario Galaxy or the occasional party game like Super Smash Bros. Brawl, that's fine," but "it's hard not to notice the limits." With all these features removed, one would think the product would live up to its name in size and form factor, but sadly, Trusted Reviews says the "Wii Mini isn't actually that much smaller than its predecessor," and Nintendo Life thinks it feels "a little cheaper and less dependable."
You're better off just picking up an original Wii unit for $150 new, or, with 100m units sold, there's bound to be plenty of used Wii consoles out there for sale for much less. The Wii as a system still has a lot to offer, but the Wii mini is incapable of providing it.