I would definitely say that an onza bird is a good bike I have been riding one for about 3 months now but when you start to progress a bit more you will wish you bought a second hand one because the tyres are shit, brake pads need upgrading and in the first month the non drive side crank rounded of but thats probably my fault.
when I started I did trials on a heavy dmr drone for 6 months and as soon as I got on the onza bird it felt as light as a feather for doing everything.