I have used Aerospike, MongoDB and Redis and have tested many other NoSQL databases. I would say Aerospike is very good at what it does but it is different than MongoDB. Everything depends on what you are planning on using a database for. I can give you an example of what I am using my different databases for. I can also go over the differences between them and discuss the benefits of Aerospike.
MongoDB
I am using MongoDB as a SQL alternative. In my MongoDB database I have many different fields. Often times the fields are changing and I will randomly need to query on various fields. It is a very unstructured database and MongoDB is amazing at that. I have also used MongoDB as a standard key-value store. It performs well but I have had MongoDB perform sub-optimally at both transaction scale and database size scale. Admittedly, the database might have been optimized a little better but I find it very hard to find documentation on configuring MongoDB correctly in different situations.
Redis
Redis is a pure key-value store. Redis’ biggest problem is that it is purely in-memory (it will use disk as a backup but you cannot store more information than you have memory available). It is extremely fast for what it is used for. I personally use it for a small transactional database: I do very simple functions on keys like counting how many times an event happened for a certain user. I also do quick in-memory look ups that I need mapped to different values. Redis is a great tool for a small dataset and it is extremely fast. Configuration is very easy as well.
Aerospike
I personally use Aerospike to replace Redis when it’s time to scale. From my understanding, it can be used for more. Like Redis, Aerospike is a key-value store. I believe the open source edition also supports secondary indexes which Redis does not (I have not used secondary indexes in production but have done little testing on them).
Aerospike’s best feature is its ability to scale. The biggest problem I needed to solve when looking into Aerospike was scaling my system to handle large data sets while remaining extremely fast. The project I use Aerospike for has very stringent requirements on speed. I usually make 3-4 database lookups plus other processing and need to have sub-50ms transaction times. A few look-ups are on data sets which are 300GB+. I could not find a solution to hold this data and make it accessible in a reasonable amount of time. Redis obviously won’t work unless I had a machine which had 300GB+ of RAM. MongoDB started to perform extremely poorly at a size much lower than 300GB. So I gave Aerospike a shot, and it was able to handle everything very well. The best thing about Aerospike: as my data set has grown I have not had to do much more than standing up a new box when needed. The speed has stayed consistent.
I also find Aerospikes documentation very good. It isn’t too hard to configure and it’s pretty easy to find answers for any issue that comes up.
Conclusion
So, is Aerospike is as good as they claim? Personally, I have seen nothing less than what has been claimed. I haven’t had to scale to 1 million TPS but I do believe with enough hardware that would be possible. I also believe the numbers showing a speed difference between Aerospike and MongoDB. Aerospike is a much more “configured” and “planned out” database than MongoDB. Because of this Aerospike will be much faster at scale than MongoDB. It only has to worry about a single (or in case of secondary indices, a few hundred) indexes unlike MongoDB which can change dynamically. The question you really need to be asking is what you are trying to accomplish with your database. Then look into which database will fit your needs best. If you need a scalable, fast, key-value store database I would say Aerospike is probably the best out there.
Let me know if you have any specific questions or need anything clarified. I would probably be able to help you out.