5stars for idea but 1star for implementation.
1. Extremely low quality of inserted images.
2. No way to specify target width, height and quality of individual image.
3. No way to specify quality for all images (default quality).
Fix this and I'll give you 5stars.
In fact, by now it's much better to just create an album for frequently used images and insert them as photos and not via Stickers. Yes, 2 more taps, but original quality.