Oximeters: Junk or Not?

There are a ton of posts on oximeters. I just cant get past all of the customer reviews on Amazon and similar sites referring to major issues with durability, some issues with accuracy, and no customer support when things go wrong. Though I see many cp-talk users are using them and finding them at least acceptable. I hesitate to purchase products that have quality issues and am a bit stuck as to how to proceed. Would appreciate insights on products that may be more reliable and durable, and would also like to know how the oximeters are helping people to improve their therapy. Many thanks for any insights.