This category promises the largest numbers in marketing software and delivers them least reliably, for a reason that has little to do with the products: most sites do not have the traffic to detect the effects being claimed.
That is the first thing to settle, before any demo. Run the sample size calculation with your real conversion rate and a realistic minimum detectable effect. If the answer is that a two-week test can only detect a 30 percent improvement, then a tool splitting your traffic into six personalized segments will produce confident dashboards built on noise. No vendor will raise this, because it disqualifies most of the market.
Where the category earns its price is at genuine volume, on high-intent pages, with a permanent holdout group so lift is measured against a concurrent control rather than against last quarter. Ecommerce product recommendations are the clearest case, because the data is dense and the feedback loop is short.
Two technical details decide whether an implementation helps or hurts. Flicker, where the original content paints before the personalized version replaces it, costs conversions on exactly the slow connections where you can least afford it. And the cold start, because a first-time anonymous visitor is most of your traffic and has no behavioural history for a model to work from.
Reviews here lead with the traffic threshold, the measurement method and the performance cost, before any feature list.