What I like best in using SAPUI5 is that it almost capture every standard process of the old ERP and tried to create templates, snippets and automatic code-generation that would best fit the intention. I tried it for free in one of the online course I took. I like that the documentation is rich from the setting up of the data set, to the navigation, to the smart controls and up to tht User Interface.
What I don't like is the data mapping of the data I want to show to the smart controls used. When I tried to create an application, using WEB IDE hosted in Hana Cloud Platform, I find it difficult to map the data I prepared to the user interface. Given that problem, I tried to manipulate my data in a way that I know would be a problem when real data increase exponentially.
I would like to recommend OpenUI5 to my fellow SAP Consultant ABAP Developers to learn the new face of SAP HANA since I greatly feel that OpenUI5 would be the very demand of SAP in next years. So if they want to ride that tide, I say, they need to deep dive in the OpenUI5.
One of the best things is that OpenUI5 is free and Open Source. Also, the fact that is is responsive across all browsers and devices makes this extremely helpful to deploy to users.
Its from SAP... Which means big and clunky.
We used OpenUI5 to write SAP Fiori apps to get HR, time entry, and inventory tracking applications. They were extremely simple to deploy...one of the best features.