Hans is the most hilarious and fun character probably in any TV show I have ever seen. I would watch this show just for him. Of course Maria is the other side of the coin - funny, petite, cute and a little bit sexy as well (Yvette tries hard, but just doesn't come off as that unique - she could've been replaced more easily - Maria had a personality).
Too bad both of them left, and after that, the show lost its 'flow' and became a bit more rigid and repetitive, with annoying characters added and the same jokes in every episode. It was still funny sometimes, but not as unique and entertaining anymore. Crabtree and the bulgy-eyed cartoon character girl just weren't the same.
Hans and Maria had the perfect balance between 'realistic' and 'humorous' - but the new characters relied on a stupid gimmick (can't ever learn french, so he mispronounces words, ha ha) and a completely over-the-top personality that isn't relatable whatsoever (Maria's character seemed still believable within all the funniness and quirks).
Hans was a great, playful comic relief and counterbalance to the more grumpy, serious and angry superior's orderbarking nature. Without Hans and Maria, the show became very unbalanced, and sometimes almost a pain to watch.