Current Hubspot scoring is severally lacking compared to its competitors. Hubspots scoring issues are so large that I would strongly warn anyone from choosing Hubspot until they fixed how they score Contacts.
1.) Allow the Hubspot Score to be completely be reset. Right now you can only give negative criteria which causes a bunch of different issues.
2.) Make it possible for new scoring rules, or changes to existing scoring rules, only effect Contacts going forward. If you change a lead scoring criteria, it will retroactively update all your records. If you have any sort of automation associated with the Lead Scoring, such as a head off process from Marketing to Sales, this causes a huge nightmare. Scoring changes should occur FREQUENTLY based on feedback from Sales or conversion analytics. Right now its very difficult to make any changes to scoring because of this limitation.
3.) Show scoring for individual line items within the Contact's Detail Screen and within the Hubspot / Salesforce Visualforce component. Having to "Test" a Contact against your scoring rules is time consuming and inefficient. No one wants to scroll through a giant list of criteria to see if a specific Contact meets a criteria.
4.) Change the way scoring occurs so more generic rules can be set. If you have a new Webinar, whitepaper, etc you're basically forced to create an entire new scoring rule for that specific campaign. You could do it based on a "Type" of campaign or some other Salesforce field, but then you face the issue of creating separate rules for every time the Contact meets the criteria. For example say you have a rule that says if Type = Webinar, give the Contact 10 points... well that works for the first time they meet the criteria. If you want them to be scored for each time they watch a new webinar based on a type field, you're forced to duplicate the scoring rule and specify that they've watched a webinar 2 or more times. The same goes for email clicks. If you want a Contact to be scored for every email click, and not just the first time they meet the criteria, you will have to duplicate the rule out several times and specify within the rule that they've clicked a link at least 2+ times.
These are just a few of the major issues I've faced when creating a scoring process within Hubspot. It needs a lot of work.