They are simple to use and provide consistent and reliable readings, as long as a sufficient sample fills a fresh, appropriately-coded, test strip and fresh control solutions are routinely used to validate meter results. You shouldn't expect your glucometer which measures capillary blood to exactly match the reading the vet gets with a venous blood sample on a lab instrument , though they can come pretty close. You will get to know what the numbers mean as far as how your cat or dog feels and acts, to know what numbers are too high or too low, and what range is normal for your pet. Your cat won't hate you for doing ear pricks. Your dog won't hate you for doing lip pricks.
Most pets accept BG tests as routine, especially when food regularly follows.
If you can stay calm while you do it, your pet will likely be calm too. Some cats purr through the whole procedure. As impossible as it may sound now, BG testing can be a pleasant, bonding experience, a special attention time for your pet. The primary considerations are small sample size, ease of meter use, and ease of obtaining a reliable sample. Pets will move when you try to test them.