Unimproved mobile game
One example is the lack of an onscreen minimap, which is pretty much standard on PC and console games. With Dungeon Defenders, you have to press a key to activate a full-screen minimap, which makes perfect sense on a mobile device, since a small permanent minimap would be too small to be useful.
But this solution is unsatisfactory, because you're often too busy to interrupt the game for checking the minimap. Also, because the minimap is not permanent, you have to find out where you are on it and how the screen is rotated in relation to it, which costs valuable time.
So a small, permanent onscreen minimap would be much better, but we still have the solution for mobile devices.
Another example is the very restricted field of view, which again makes sense for mobile devices with a very small display.
On a PC or console, the field of view should be considerably larger, because the way it is you can not see much of what's going on around you, and, as mentioned before, checking the minimap is a hassle.
If you're not playing the english version: the translation has obviously been done with something like google translate.
Some translations are understandable, with some you can figure out what they're meant to mean if you know english well, and with some it's totally unclear what they mean.
The network issues supposedly have been improved, but you can still expect disconnects and occasional loss of data when playing online.
All in all I can see how this game has it's use on a mobile device, but it looks like a cheap port to the new platforms that I would not like to play more than a couple of hours in total.