Well, I haven't played with University Life in 3 years but Ambitions is the first pack I install. I do like Twinbrook (although sims aren't as good-looking as in University Life) and the new careers introduced. There's only one floor lamp that I really dislike and I believe there's a bug with the lifetime wish related to the architectural designer. Some mods enhance and fix a couple of details. For example, there's a mod that allows the Consigment Store to buy more stuff and another that doesn't allow the stylist's studio to reset your sim's age bar.
Your comment on the Ambitions jobs is also right. It's cool to experience them with just one of the sims in the household. They do get repetitive after a while and some of them are demanding. I have played all of them and I think it's nice to play them once in a while.
UL can also get really dull as well if you send your sims there every generation. Frankly, the social groups and the advanced cell phone didn't catch my eye. The new lot types are cool, but it would be nice if there were smaller options in the bin. I also agree with GraceyManor, UL is great for several items and clothing (hairstyles are much better than in Ambitions).