1) Capabilities. It's one of the best - if not the best - social media tool to keep track of feeds. I've found nothing that can match its ability to search and monitor keywords or accounts.
2) It does have a free option. While it's very limiting, for some users it may be a nicer alternative to spending a lot of money on a monthly subscription.
3) It's not hard to understand.
1) It's really outdated as far as its design goes. It looks like it was awesome in 2010 (which is was) and then never really changed its interface.
2) Not everything is included, even if you pay for it. Reports, for example, cost extra. No bueno.
3) It's really clunky. For example, I use it primarily to monitor keywords and account streams. I then take the tweets and retweets and load it to eClincher, my preferred scheduling system. The issue is that it refreshes (which is not a terrible thing) but because it's so massive, it often freezes my Hootsuite or makes it otherwise impossible to do anything until the refresh is completed. It's frustrating to want to check on a link only to have to wait 1-2 minutes in order to do so. In addition, as it refreshes, it has a nasty habit of sometimes of automatically updating the feed. I can't tell you how many times I've clicked to edit a retweet only to have it update. I end up opening the tweet above it instead or (worse yet) I'll accidentally click on retweet instead.
4) It's scheduling is time-consuming and frustrating. It's not the most effective system for scheduling.