At my company we use act it's decent but as we grew over the last 10 years their per user license fees really added up. If your at a big growing company paying for any software on a per user basis is painful. I had a web vendor 3 years back who wanted to charge us by the user. It was a marketing platform that was to be inserted into our website at $10 at user. It was a great product but we walked away from that one. Last I check we had over 20,000 users at our website...that would of cost us $200000. Nice.
So my advice is watch out for those per user fees...think what if?
All good points...as I mentioned before we spend way too much on ACT ..however outlook is pretty weak compared to what is needed. I can understand using it if you have already spent thousands of dollars on an exchange server infrastructure and have the IT staff around to keep it running...married to a Exchange server you get some more features from outlook that help it along. Also if you spend that much on an exchange server you have to use it (outlook). One of the big problems with outlook is a lack of customization. Out of the box it is very generic and not industry specific. It's also not the best workflow engine. Most of our sales people don't really like it because they can't customize it enough....don't take my word for it read 67 reasons outlook sucks.. http://wanderingstan.com/2008-02-01/67_reasons_that_outlook_sucks