Versai

Versai has perfect and seamless integration across its wide range of functions (e.g. Membership, Admissions POS and Group Registration, Retail POS and Inventory Management , Web, Development, Reporting). I cannot overstate how important this is to us, and how well Versai has pulled it off.
It's easy to train new cashiers on how to use it, and it's intuitive for back-office users as well.
I was skeptical about the web integration at first, but now that we've been using it for a couple years, I find it hard to imagine functioning without it. The cost is more than offset by the savings in staff time because our customers can get what they need (buy/renew memberships, register for birthday parties and special events) online.
The support team is great, and the development team truly listens to feedback from their client base to continuously improve the software and implement the most requested new features.

The financial reports are all based on cash accounting as opposed to accrual accounting. I'm not an accountant, but I'm told by our finance team that this is a real drawback for larger organizations like us.
The web tools are not very strong. There is limited control over appearance and functionality that doesn't always allow us to do what we'd like to do for brand management and optimal user experience. I suspect this is somewhat intentional on Versai's part in order to maintain clean data and to keep things simple for sites that don't have in-house web developers, but it can be a limitation for advanced users.
Reporting is generally good, but we sometimes run up against limitations. We provide education programs now for three different organizations, all under a single umbrella, so it gets complicated. We've had to really push the reporting tools beyond what they are intended to do in order to make it work.
The software can be slow sometimes. Its unclear whether this is due to hardware problems on our end, or software problems. I suspect that it's a combination of issues.

It's customizable. All users have access to the same reports. Centralized patron records. Allows web sales.

As a small museum, we utilize every aspect/module of this software. It cannot produce mailing labels from database. Needs 'manager over ride' options: performance times (changes after sales), edits/corrections to refund line. Multiple patron record duplicates can be created by web purchases. Generic reporting. Enormous amount of wasted time waiting for some reports to generate. Queries: very confusing - unless familiar with computer programming. Areas "Coming Soon" - have not arrived after two years. Customer service issues must start on their web based forum - no phone calls. No detailed user manual available at this time.

The total integration approach works well for our organization. Having a members be recognized at multiple sales points in their visit is invaluable.
The auditing ability is great.

Number of clicks to make a sale slows down the check in process.
Not intuitive
Reports difficult to customize and get data for the common administrative user
Venue based and we are program based

It allows us to use the same system for all of our income departments, with detailed, real-time reporting. We also love the simplicity of comparing current to past statistics. When we have questions or problems or need help, the customer service is fast and top notch!

I wish it included accounts payable component. We are also hoping for a volunteer management component.