I use Qt5 extensively and these are the things I don&#x27;t like (mostly QML-specific):<p>* It&#x27;s HUGE. A &quot;hello world&quot; QML program is like 50 MB. You can get it down to about 20 MB is you use a custom Unicode library build (there is a 20 MB DLL which just contains Unicode data).<p>* The QML compiler is only in the commercial version. I know there is a third party open source version, but that is too much hassle. And yeah maybe I should pay, but hey!<p>* Lots of things still are impossible with QML. There&#x27;s no decent basic text widget (e.g. for a log output).<p>* You can make custom QML widgets, but they can&#x27;t render text. Kind of limiting!<p>* I don&#x27;t think the basic premise of QML works that well. There is such a big difference between C++ types and QML types most of your code ends up dealing with the mapping. Especially lists of things are very hard to get right (and the documentation doesn&#x27;t really point you to the &quot;right&quot; solution - which is to subclass QAbstractListModel if you were wondering).<p>* QML seems very hacky and javascripty - it doesn&#x27;t scale well. Especially scopes and id&#x27;s.<p>* Some QML things are weirdly hard, for example<p>- Rich tooltips<p>- Adding padding around list items<p>- Doing anything with the rich text widget.<p>That said, I still really like it. I&#x27;d just like it more if they:<p>1. Reduce the size.<p>2. Redo QML (again!). I&#x27;d be even ok with a custom language. It can be similar to Javascript, but it should support the native C++ Qt types (and custom ones) much easier.