Realistically, the NSI Classic Tumbler is made for kids, so in terms of “cons” there are none really which would equate to making this a poor product. Naturally, compared to more expensive models it cannot hold as much rock, but when comparing “like for like” the NSI is a good all round introduction to the craft.
Perhaps the barrel could hold a bit more rock, but again, for a starter kit this isn’t really an issue.
Only one barrel can make the final polish phase a little bit tricky which will definately worsen over time as more and more grit particles contaminate the barrel. So longevity could be an issue, but keeping it clean by painstakingly getting rid of all particles after each batch will make it last longer.
The red barrel is a tad on the thin side, again this is more of a lifetime issue than a major problem as the rocks tumble fine.
May need to give it a little push with your hands to get it rotating – but this is no problem as once it gets going it keeps rolling. We have seen this on a number of different rock tumblers and they are normally the ones built for kids, the NSI has this minor quirk, and with heavy loads – some of the more expensive units do aswell. If it doesn’t keep rolling then it would be a faulty one – but this is probably a rarity.
We have seen reports of barrel leaks – however again, this can be a common problem on the kids models. Keep your eye out as you don’t want the contents of a given tumble spilling out.