I've been an ACT user since the mid 90's. However, the companies that I worked for started using Exchange Server, Outlook would sync to my phone, my web and of course to multiple Outlooks. This made Outlook considerably more appealing. Now that ACT 2011 syncs to Outlook, I'm back.
Now that I'm back, it is hard not to compare the two. The biggest problem that I have with ACT (Verses Outlook) is that there is no "Company" phone number. Typically a contact has a company phone, and a direct line in. The direct line could be a home office or just a DDI to their desk phone. Either way, both numbers are useful. In Outlook, it is easy to have multiple numbers for each contact and I certainly took advantage of the "Company" and the "Business" numbers. Unfortunately, the outlook "Company" number does not sync with ACT. In fact, the only way to get the company number in ACT is to either create it as a custom field and copy and past data from outlook, or the use the Phone Field from the company view in ACT. Both of these are crude given the initial investment and subsequent upgrade cost associated with ACT. There is no customizable mapping with ACT and Outlook, despite the many additional fields that Outlook has.
I noticed that Outlook Journal entries (the comparable to Notes in ACT) don’t synchronize or come across. That is to bad.
I would certainly add a "Company" or "Organization" or "Main" phone to ACT and have it sync with "Company Phone" in Outlook.
I would also make the Search easier. In outlook it is easy and simple. Type in keyword, and enter. In ACT you have to Click the Search, Click Last name- first name Etc, or click on keywords, then click the Starts with- Contains, and finally enter. In addition, I forgot how much of a pain it is to have the separate Search view in Act verses the standard list view.