Is there any limit to size of HTML Assets or any other things to watch out for?

With HTML assets, memory usage can become an issue if the asset is not designed well.

For large assets, avoid a single index.html with excessive <div> tags with lots of rendered images as backgrounds, as these images will need to be retina quality (2x the resolution) and loading all images for an asset for multiple pages, will more often than not crash the app due to excessive memory usage.

Similarly assets that work on an iPad3 may not work on an iPad2 as the memory available on both devices differs, so make your asset work for the lowest device version the client uses, it will work for all the newer models too.

If you want to swipe between pages, use a method that loads different html pages, rather than many <div>, for the same reason as above.

There are instances where fancy/complex video JavaScript libraries are used to open a video full screen with animation, some of these libraries have been found to cause a crash to the application possibly due to memory usage.