Let me start with saying this was our experience and our opinion is based on our previous experiences with the Vibe. We are a family that does utilize the Vibe for around three hours in the morning, then around four hours in the afternoon on sea days, then we always head right to the Vibe for a few more hours after we get back on board the ship on port days. Also, I do not know how the Haven sundeck compares on other ships as our experience is with the Joy.
We sailed on the Joy in the Haven last February. Even though the ship was at a very low capacity, the Haven was fully booked due to upgrades which is the new norm. We found that there really was not a lot of good lounge chairs as about one third of them are the uncomfortable ones and those were the ones near the railing which is usually where we like to set up. Unlike the Vibe, it was always crowded and sometimes it was hard to get loungers in the afternoons which is something we never experienced in the Vibe. The bar service was extremely slow and sometimes non-existent. My husband would end up going down (one deck below) to get our drinks. Seven months later we went on the Joy again in a non-Haven Suite and had put in upgrade offers for the Haven. Then when the online purchases of the Vibe tickets started, we immediately purchased our tickets and cancelled our Haven upgrade bids.