We have both Teradata and Exadata where we work. Exadata just blows it away. A lot of Teradata stuff is very immature compared to Oracle (no online backups, they use Oracle GoldenGate for replication to a standby site, etc). Another key difference is how Oracle handles read consistency.
Our Exadata DW is wanted more and more by developers and application owners alike - our data and usage growth are very significant. Nobody wants to touch Teradata with a bargepole - they basically can't use the system if more than two or three end users are hitting the DB. Only this week, Teradata announced unilaterally that they were going to stop informing us of hardware failures. Guess what happened within 24 hours? We lost an array controller.
I cannot see how Teradata holds a candle to Exadata, to be honest. Exadata's performance just SCREAMS!
Microsoft PDW have been pushing hard lately too. Their setup is more like Teradata than Exadata (commodity hardware, share-nothing architecture).
In my previous organization we had 70+ analyst constantly querying to tables with millions and billions of rows in teradata. and it worked well.
If the schema is well designed we get single source of truth and I have created cube reports with 6+ dimentions in a single sheet excel with no errors from TD.
I wonder how there can be problem with a such a few number of work station? even Oracle ( without exadata) will not give problem with such a small number of work station.
Technology wise both are doing good. Each technology has its own value and features.
Teradata was well known for Dataware Housing (DWH), now Oracle Exadata also entered in this segment.
Career-wise as a DBA, both are value if you learn consistently.
Features are :
1. Oracle Exadata and TeraData will support OLTP and EDW.
2. Oracle Exadata and TeraData will support Linux Operating System. Oracle Exadata can port in Solaris also (x86).
3. Teradata - 10 Gigabit Ethernet Interconnect Node to Node & Oracle Exadata - 40 GBps Infiniband Switch between compute node and storage. May be in future Teradata also will look for higher bandwidth.
4. 96 GB Memory in each node in Teradata. 256 GB memory in Oracle Exadata (x3-2) recently upgraded feature in x3-2
5. Eight Nodes will have in Teradata. Oracle Exadata will have Eighth, Quarter, Half and Full Racks.
6. Teradata and Exadata are ACID supports.
7. Teradata 30% compression and even Exadata also.
Both are equally good and both have very future in OLTP and DWH Projects.