An updated review after having played the game to completion...
Only buy this game if you are prepared to battle a few technical issues, but if so, then certainly
do. And especially when on sale. Point & click fans should not mis this one: it's great fun.
The tl;dr version: you will want to install the 7u79 Java 7 JRE and will if playing the English language version need to change to German for one of the puzzles (the kitchen menu one) and for the ending credits, but that's it. Steam-achievements worked fine for me with either language.
For a bit more detail; it is as to the first and foremost technical issue as of 2015-07-14 likely that the game won't run fullscreen for you after initial install, presenting you with a white screen with sound only and no picture. This is a Java version mismatch. The first run of the game installs the very first version of the 32-bit Java 7 JRE (7.0.0), which at the very least on Windows 7 64-bit does not in fact work for this game.
If you do not need a version 8 JRE installed for other purposes, it's easy to fix. Install the latest and last version of the 32-bit (i.e., "x86") Java 7 JRE manually; version 7u79, released 2015-04-14, at the time of writing available fromhttp://www.oracle.com/technetwork/java/javase/downloads/jre7-downloads-1880261.html
If you allow the installation to remove the 7.0.0 version, running the game will reinstall it alongside again but it seems to in fact still use
the new version. It for me runs fine after installing 7u79.
You do currently need to not let the just installed new JRE7 subsequently update itself to JRE8; this at the moment installs the 8u51 JRE and will see the game return to its original white-screen behavior. This may of course have changed by the time you read this, but if not, I would advice to simply temporarily uninstall JRE8 for the duration of playing the game. Some 20 hours, that is.
Note that if you insist on not even being offered the upgrade to JRE8 by the JRE7 you will find the relevant option in the Java 32-bit control panel to not stick unless you run it as administrator. If the account that you are running Steam and the game under has administrative rights, this consists of right-clicking
C:\Program Files (x86)\Java\jre7\bin\javacpl.exe
and choosing "Run as adminstrator". If you run Steam and the game under an unprivileged user account, temporarily give
this user administrative rights, only to unselect automatic updates as per the above. And blame Oracle. You may or may not have to repeat this for the old 7.0.0 version as installed by the game and as found at
C:\Program Files (x86)\Java\jre1.7.0\bin\javacpl.exe
At this point you should be able to start enjoying a very good adventure game, fullscreen or windowed, and in either English or German.
Unless you luck through it, it is likely that you will get the game stuck inside the kitchen-menu puzzle if you play the English language version. If so, Alt-Tab to your desktop, end the game by right-clicking it on the taskbar and restart in German. You can quit and restart in English again immediately after solving the puzzle. The English-language version of the ending-credits is also bugged currently; same solution applies.
If you read to here, you're probably wondering if this game is worth the hassle. Yes, I would say it is. In fact, I consider the game an instant (not-)modern point & click classic. Be sure to check out the sequel, "Edna & Harvey: Harvey's New Eyes" as well; a more modern interface and every bit as entertaining.