We done Brewhemia last year and I thought it was awful.
Granted I was never likely to be a fan but the tables for food were right below the band so you were eating food whilst people danced around you. Service was slow, food was poor (undercooked roast potatoes the highlight), £5.95 a pint of poorly kept beer, the 'entertainers' were cringeworthy and it was just a bit crap. On the flip side a fair few women in the office thought it was great.
Not much help really other than to say avoid Brewhemia. 4 or 5 of us left early and just went on a bit of a pub crawl and had a great night. I understand it's logistically difficult for big teams but something sporadic just seems more fun to me. The forced fun of party nights or over planning of big sit down meals just annoys me. People spend so long talking about it that I'm sick of it before it starts.