With that magnification (30) and smallish object lens (50) the light transmission will be greatly reduced. Ideally, the object lens should be 4 times the magnification but this is difficult to realise in a scope. So, for example, in poor light or cloudy weather you may find it to be inadequate. That advert doesn't mention a price but for a reasonable spotting scope expect to pay something in excess of £1k. Cheaper one are available but, as with most things, you get what you pay for.
I have a pair of Zeiss 15x60 bins which I find very adequate for spotting. My wife and I also have several good quality bird spotting scopes of higher power (40x80) but they need good light and a tripod. A handheld scope takes a lot of getting used to so expect to have to steady it against a building or tree.
Lastly, zoom lenses are never as good as a single magnification lens.
HTH