it works, it's pretty and it's robust - firemonkey is certainly a great off the shelf choice for people looking to easily develop unique looking apps but lack any sort of technical knowledge or need of hardware accelerated APIs.

But that's the kicker - we're game developers - if you're talking 3D acceleration, games you're also talking performance, cross platform flexibility - firemonkey simply isn't designed to work inside an existing engine/framework - it's designed to *be* the framework. It uses a ton of memory (I assume it has to be creating back-buffers for every control to use as much as it does) , it doesn't give you full control over GL initialisation (very important) or the 'render loop'.

If you're not using the 3D hardware outside of what firemonkey directly gives you - and you can afford it, then sure, brilliant, firemonkey is pretty and it works.

But it's not very suitable as the GUI for a 3D game for example - that needs total control and utilisation of the hardware - this doesn't include every project - not at all - but it becomes an issue eventually so unless you're absolutely certain your project won't grow? it's worth thinking about.