Sorry to say I haven't used this lathe or any specific cue lathe. However, I have worked with general purpose lathes and received some general metalworking training from an associate who's a model maker. So everything below is just based on my opinions which I gathered based on the Ebay listing description... I could be wrong about how effective this thing is, but I'm not wrong about the flaws I point out.
Whether the lathe is worth it or not really depends on your expectations. I would not expect to use this lathe for much more than tip repair and some light shaft work (using sandpaper for surface clean-up, maybe ferrule clean-up). I would not expect to replace the ferrule, change the diameter or taper of the shaft as they suggest, or do any wood cutting of the shaft.
I think the picutres show a lot...
The bed of the lathe is flimsy and will be prone to deflection (bending) and chatter (vibration) when trying to make any moderate to heavy cuts.
There is no tailstock, so it completely relies on the accuracy of the of the bed and steadyrest to assume the shaft is properly aligned in the lathe.
This lathe doesn't have a proper tool post/support, so it really depends on the operator to have solid control and a good touch with the cutting tool... More than the would on a wood lathe type tool post. That control doesn't come easy and it takes a lot of mistakes to pick-up good technique.
This lathe assumes you have a good eye and measuring tools, even if the fine print doesn't say so (it doesn't have any tool feed mechanism, so you have to cut by hand and measure by eye and constantly measure).
These example issues are fine if you want to change a tip or just run some sandpaper of the shafts spinning surface to clean it up, as I mentioned before... But again, if you are trying to replace that ferrule or reduce your shaft diameter as they suggest I can't imagine you could pull off a quality job... I wouldn't even try it on a scrap shaft because I wouldn't want to waste the time... I could be watching TV or playing pool.
Pool cue work (beyond tip replacement and sanding) actually requires a good lathe, and one with metal lathe features (toolpost with tool fixture, feed dials, tailstock, a heavy duty bed). I woudn't work on my cue shaft in even a quality wood lathe unless I just wanted to do the most basic work.
So if you want those simple features, keep in mind you don't need a lathe to replace a tip or polish a shaft. This lathe is not a scam, because I would think that if you are determined and have flexible standards, and invest some more money in tools/modifications you could probably learn to replace ferrules and turn shafts... But it's going to be a pain.
I also think this will be a case of getting what you pay for... Lathes are not cheap, even small cheap ones that are too small to do cue work aren't actually cheap. The practical "pool repair" lathes (Cue Smith) that have come to market are a mixed bag of compromizes in order to bring the price down yet still deliver core features that effectively let you do some volume work to maintain cues. But this specific cue lathe just really takes it down to a level that does not seem effective.
I'd just put my $ to tip replacement tools, or buy a scrap shaft and learn how to do them by hand. If your goal is to have a little side-business to do maintenance work, I'd buy a proper cue lathe... If your side-work will pay back for this cheapie lathe, it will also pay back for a better one at 4 or 5 times the cost.
Good luck.