I've been very pleased with mine for the 10-11 months that I've had it. I've used it for 25 or so gigs when i didn't want to tote around a bigger mixer.
The effects, while not stellar, are usuable. Same with EQ and comp. I've been able to make it work just fine. Again, this is a 'smaller gig' mixer. I've done some small clubs, some corporate.
The iPad app has occasionally dropped out, but seems to always immediately re-sync on it's own, taking less than 10 seconds do it.
The input trim pots are a little flimsy and too easy to turn. They are so close together that you might bump one while adjusting another. Johnny Medina, who travels with Marcia Ball and uses the mixer every night, came up with a clever way of putting lock washers on the pots to make them harder to turn and stay in place.
The connector at the end of the slot to use the iPad as a Wired (and self-powered) device is a little worrisome. a) I'm wondering how many times you can slide it in to connect before it wears out. b) If you ever use iPad 1, you have to install the little hardware pieces to make it work. An extra PITA if the iPad 1 is used in a 1 off situation c) the connect doesn't work for the current and future versions cause Apple modified the connector.
That being said, the quirks aren't that big of a deal. I've enjoyed using it and will do so many times again. Cost to me was only $1000 since I already had a router and iPad. It will likely get a little less use when I get the X32 Rack, which for only $500 more will give me a much deeper feature set, especially since I already use the X32 and 2 S16 stage boxes. I'll probably sell mine at that point, not because I don't like it, but just because the X32 Rack will integrate more seamlessly with my usual workflow.