Let me start by saying this is probably the cheapest LED diabolo on the market and as such you'd expect to find a few faults with it BUT there really aren't many! The only issue I had with mine was that the weight was slightly more to one side than the other but a brief go on the pliers to reposition the main thread through the axle and it was right as rain... don't let that put you off though, it was easy to fix and a friend's one didn't even have that little wrong with it!
This diabolo is capable of attaining quite high speeds for sustained spin, grinds, string climbing, whatever you may desire it to do really, although the axle is quite narrow so it will slow down a bit if you wrap the string. The cups are slightly flexible but sturdy enough and round enough to enable bounce tricks with relative ease...
...And the LEDs? Well, they're actually surprisingly bright (I sometimes use mine as a torch when out spinning at night), and make it really easy to see for catching, producing a pleasant spiraled pattern in long exposure photos. The batteries are easy to replace and so far (after 1 year) I've only had to replace them twice and none of the LEDs have broken either!
I do have a word of caution with this diabolo though and that is DON'T GET ANY PARAFFIN ON IT!!! The material the cups are made from will warp and melt out of shape if it gets any fuel on it and the results seem to be quite drastic rendering it almost totally unusable (thankfully it wasn't my one that taught me this)... but if you're sensible and don't store it next to fuel or fuel soaked toys then you'll be fine!
All round a good entry level, low price LED diabolo that's always entertaining and worth every penny!