Contrary to what alot of people are saying here, I'd say if you have the money to buy it, get it. Market Samurai is ok for Keyword Research, but as far as doing in depth competitor research Market Samurai has been known to return inaccurate results (which is why they took their forum down).
The details that Spyglass gives you is totally under your control. You can pick how much data you want. You can limit it just for PR, or you can get an entire birds-eye-view of what someone's backlink portfolio looks like. Yes you can go to Google and Ctrl-F, yes you can import/export all of this data into Excel, yes you can do this or that, but the point of using this software is so that you wont have to. I dont use Link Assistant, but Rank Tracker, SpyGlass, and Web Auditor I use on a regular basis. The rank tracker is faster than Market Samurai, Spyglass shows you EVERYTHING on screen from Anchor Text, whether or not a link is alive or dead, PR of the referring domain, etc. etc., and Web Auditor can help you improve your Onpage SEO score relative to your competitors.
BTW, the pirated version in the forum no longer works, that serial is dead so you'll have to pay for it (like I did) if you want to use a legit copy.