I have four favorite things about Union Metrics.
1.) Their customer service/account reps are very helpful and quick to respond on any and all questions.
2.) Their interface is very clean and beautiful to read.
3.) Clients/brands can have their own logins to view (not edit) hashtag data for their campaigns.
4.) There is a firehose for Twitter that allows you to go back through historical data from 30 days ago, 1 year ago, or lifetime depending on your account tier.
The only dislike my team and I have about Union Metrics if you haven't generated a report for a twitter topic/hashtag yet and someone deletes their tweet their impressions are not counted. However, this is an issue with Twitter. If there was a way to automatically generate a report every 12-24 hours we think this would solve this problem.