#1 Very basic selection of audio and subtitle language via remote and too small font
When changing the subtitle or audio language via the remote control, a very small box appears with the current selection. The font size is ok on a PC monitor, but on a TV in 3m distance, it's too small.
Besides most standalone players display more than the currently selected language. Some show all available languages and let you choose it, some show at least a few (3..5) language options at once, so you don't skip the language you want accidentally.
-> I'd really like a more user friendly solution there

#2 Fast forward/reverse in media files
In AVIs that I can fast forward/backward up to 8x on my Dune HD player, PowerDVD 12 only offers forward speeds from 1.0 to 2.0 and refuses to wind backwards. Again, this might be ok on for the PC application, were you can use the progress bar with the mouse. However in a TV use case, were PowerDVD runs on a HTPC next to the TV and is controlled via the remote app, this kinda cripples the remote control concept.
Besides, even if the video player component in PowerDVD is not able to implement fast foward/reverse in certain stream types (even though other players can do this), there should be at least an option to skip forward/reverse in e.g. 15s steps. Buttons for skipping forward/backward are really missing in the remote control app.

#3 Remote control app functionality
Every time I start the remote control app on my iPod, it first forces me to re-select the server and then asks me to activate the location services. Instead it should at least optionally connect to the last server and allow me to disable the "location services" dialog. Anyway, it's beyond me why a remote control app needs locations services at all.
Besides, neither the iOS nor the Android App show anything in the "Movie" view even if a selection is displayed in PowerDVD itself. I would expect that if I select e.g. a folder on an USB stick and PowerDVD shows all files there that the remote app will also be able to display all these titles in the "Movie" view, but it doesn't.
Even worse: when you change from the remote view to the "Modules" view and then back, the remote control usually stops to work. At least if you just played a media file from e.g. an USB stick. Sometimes an error message pops up for a short time that indicates that PowerDVD tries to play a BD/DVD from the default drive. Anyway, there is no way then to resolve this issue with the remote app alone. You have to stop the video playback from PowerDVD, start it again and then also the remote control app usually works again.
Last but not least, the (iOS) app keeps asking me to enter the pin to connect to the server without any clear reason or pattern. I think the Android app is less buggy in this regard, but maybe I haven't used it long enough (I installed the iOS app on my iPod and the Android app on my Galaxy S2 just to compare them - only one runs at a time though).

#3 Remote control app layout
The layout of the virtual remote control in the app is a bit too basic. E.g. there doesn't seem to be a "top menu" key for Blu-Rays (only popu menu). There is neither a numeric keypad nor are there keys for single frame playback or skipping forward/backward (see #2). From my point of view there should be also an option menu (TrueTheater, video/audio options etc.), and the app could really use two-way communication to e.g. display stream information or let you choose the audio/subtitle language from a list of available languages instead of simulating a dumb one-way IR control.
Besides, the keys are too small. Have a look at the official remote app for the Dune HD player in the Apple appstore to see a better example of remote control layout. The bets idea about it is that there are several fews for the remote control with different main purposes and you can easily switch between them.

#4 Navigation/user interface concept
Unfortunately, the base concept of PowerDVD is a large, but more or less static media library. I'm aware that there are people there who want this, but I know a lot of people (including myself), who don't want to keep a large media library and who don't appreciate a media player to try to collect every bit on media on every device in the network without being told to do so.
Personally, I want to insert an USB stick or connect an USB drive, point the player to this folder and then browse/play media from this folder. I don't want these files to be imported into my library, I just want to browse and play them as fast and comfortable as possible. Which includes display and selection from within the remote app.

-> at the moment PowerDVD is too much focused on the PC user, but using it as replacement for a standalone player is not really comfortable, mainly due to limitations of the remote control app and other design decision (small fonts in onscreen info displays, limitation of navigation in the stream via remote control etc).