Pros
Lots of talented, friendly, professional people at the lower levels. Most, however, seem to be limited to production only. Used to be free snacks and soft drinks (which looks like these are being eliminated or limited).
Cons
Gensler doubles management. Each office has two managing directors, each region has two managing principals, etc. These folks seem to basically just overhead, with little project time, so it is a costly way to run an office or region. The two managing directors are both interior architects - neither really seems ti know how to build a full-service architecture practice. Both seem content to stay in their private offices with very little interaction with the rest of the studios. Gensler use the term collaboration a lot (as well as "One Firm Firm"), but the firm is highly silo-ed - within offices and between branch offices. Studios rarely collaborate with each other in the same office because studio directors seem extremely territorial. Firm is hypocritical about collaboration - they say it all the time to clients but do not practice it. Management measures every employee on every possible metric. Billability is highly scrutinized and there is a very opaque system for bonuses and promotions. Whenever there is a mandatory office or studio meeting, you are usually required to makeup that time after hours.