Are mini sewing machines any good?

Generally no, and they are the commonest bad first purchase in sewing.

Why they disappoint. There is too little weight to resist the fabric, so the machine walks across the table. The feed is weak and stalls on more than a couple of layers. Presser foot lift is minimal, so anything bulky will not go under it. Tension is often fixed with no way to correct it, and bobbins may be non-standard and hard to replace. On some of them the stitch is not a lockstitch at all but a chain stitch, which unravels from the loose end if a thread is pulled.

The real cost is not the money. A beginner on a machine that jams, skips and will not hold tension concludes that they cannot sew. They cannot tell their own mistakes from the machine’s, because the machine makes one on every seam. That is what these machines take from people.

One distinction worth drawing. A genuinely lightweight full-size machine from a known manufacturer is a different object entirely — small and light, but properly made, with real tension control and standard parts. Judge by construction and brand, not by size. Handheld stitchers are different again: they are a tool for tacking a curtain hem where it hangs, not a sewing machine.

Better answers at the same money or less. A serviced second-hand machine from a dealer. A borrowed one. A part-exchange machine from a repair shop, which has been checked by someone who knows.

And if the need is one hem or one repair, a needle and thread, or a local alterations shop, is cheaper than any machine at all.