That particular only has a 4x optical zoom, so not the best, but I would say average optical zoom for that level of camera. Still good for getting to the other end of the garden from afar!
My own camera is a few models up from that one, and it has a 12x optical zoom, which is much better. Then of course, you're looking at higher prices and we're still not talking big, professional SLR level. Many cameras also come with Image Stabilisation (IS) these days, which is very handy when trying to photograph birds, especially the fast moving ones like Blue Tits.
I suggested that particular Canon as a good 'starter' camera (my wife just bought one) since you said you don't own one, although as yo can imagine, there's a lot of choice (probably too much, as is the case with almost everything nowadays) out there. But most 'budget' cameras don't have that great a zoom; anything in the £100-300 price bracket will probably come with sufficient lens capability; 10x and above.
This sounds like it should be in a camera thread...