Personally I love Majestic as a backlink tool after using it for my SEO consultancy - Matt Tutt Digital Marketing. But that's all I've really ever used it for. It seems to lack a lot of features when compared to other software, but I think that's because it's not trying to compete as an all-in-one tool. For backlinks alone it's got a massive amount of information, and if I only wanted a backlink analysis tool I'd happily subscribe to Majestic.
Downsides of Majestic - As mentioned above, Majestic is really just an offsite SEO tool to carryout backlink analysis. I would still need to pay for various other tools on top of Majestic.