I have the same problem. My HTC Desire has much better WiFi reception than my One X. I tested it with the WiFi Analyzer app and the difference in signal strength is on average 10 DBm, which is quite large difference. For me it makes WiFi unusable on the top floor of my house, where the Desire never had problems. With the One X I have set WiFi to Best WiFi in Settings, but it didn't help much.
What I also noticed are very large variations in signal strength. In a room next to the room where my WiFi router is, I should have strong signal, sometimes I have 2 arcs signal strength in the WiFi icon, but sometimes those bars drop do only the dot in the icon, so a large difference.
edit: as far as I can remember, before the update I didn't notice the WiFi problem, but that might be due to the fact I just got my phone. I haven't unlocked my bootloader so I can't test it myself, so maybe somebody else is willing to test that? It's important to find out, because if WiFi really was better before the OTA update, it means it's just a firmware issue. If not... it can be hardware.