This review is very positive about Freshdesk. But if you are planning to use Freshdesk in conjunction with a forum (bbPress in our case, fully integrated with WordPress),
you should be very aware of a huge limitation in Freshdesk: it doesn't respect the Reply-To address. Helpscout is no better.
Update 1 December 2013: Freshdesk has fixed the Reply-To Address and we've been able to fix our incoming forms to use reply-to, making our work a lot easier.
Update 25 April 2014: I've recently reviewed Freshdesk's new Freshfone feature, including extensively testing Freshfone call quality.
As many of you know, we've moved from selling just services to also selling product (FV Flowplayer, the most feature rich and intuitive HTML 5 video player for WordPress). For services, every clients gets his or her own TeamworkPM project with messages, task lists, milestones. But that kind of overkill doesn't make sense for purchased product where many people won't need support and many people will just need one or two requests answered.
Part of preparing support was improving our very active forums. But in addition to the forums for free support, with a paid product we needed an efficient help desk solution. We didn't want our customers to feel that they were in a help desk: the personal feel is very important to us. Support should be as easy as email.
When WPMU mailed us their glowing review of Help Scout we thought this is just what we needed.
When we first got our hands on Help Scout we thought it was great. Multiple shared mailboxes with internal notes.