This is my 2nd APC 650VA UPS and my 3rd with the same form factor. This one lasted 11 years. It is reasonably priced and reliable for the most part. The design has not visibly changed in ~ 20 years. There are a couple of issues which I would like to see improved. 1. The battery connection is not robust. The "slide on" connectors do not provide a good contact area and often become loose over time. This is an industry problem, but if APC want's to extend its recognition in the market place its an issue they can work to resolve. 2. The low/defective battery detection is unreliable. You don't get a lot of false failures, but you do get a lot of false "good battery" indications. As a result you (the owner) are going to spend a lot more time investigating battery failures than you want to. You may even find yourself purchasing more of those expensive batteries when the actual problem is the UPS itself.
Would I pay more for these improvements? Probably. If it saved me the several hours a year I spend investigating and resolving UPS issues then it would be worth the extra money.
Pros: Good Value
Cons: Difficult Maintenance, Low Confidence in 24/7 Uptime