E-mail applications are at this point a dime a dozen, but very few manage to integrate all the features each particular service has to offer. Thus, many times such applications offer limited support.
Still, as the name suggests in this case, WunderMail for Gmail has concentrated on integrating Gmail in its structure with all the common features a user might want to have at hand.
Now, while the developers try to make it clear to all potential customers that this is the best app for desktop Gmail integration, most of the features will most likely work on other similar apps, like Outlook Mail for example.
Amongst features highlighted for this particular app, one can enumerate push notifications for incoming emails, composing, checking mail while offline and e-mail previews through live tiles. While these could easily fall in the bells and whistles category, there are many users who'd prefer such features over a highly simplified structure, for example.
Two other specific features, in this case, are the ability to have multiple Gmail accounts active in the app and specific avatars for the people you correspond with. The latter is simply a Gmail integrated feature, meaning it was simply made available in the app as well. That means, in theory, you can use avatar images as a guide towards finding certain electronic messages.
You can't really argue that these features are not helpful, but they're not that special. If you take into consideration the fact that you must pay to remove ads, thinking about this investment will only lead to the conclusion that this app could easily be switched for something better without any charge.
WunderMail for Gmail is, in the end, no better than any other application, if you come to think about it. Why? Simply because it does not offer something that special or useful for a user to fork money instantly for it. At best, it's worth getting the app just to brag around about some debatable special features to your Gmail enthusiast friends. Not worth it, really.