If you played SM2 then NetEpic will feel familiar. There have been lots of improvements though.
- Alternating movement - no longer the I go, you go but a proper alternating activation system.
- Hidden orders/fog of war - you only reveal a units' orders as it is activated. This is quite an important change...movement can be a very tense phase

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- Titans are much stronger and able to brush aside infantry swarms and the like.
- Superheavy damage table. More durability for your superheavies.
- New costing system for titans. The more you tool them up the more they cost!
- templates for Praetorians. They become serious units now and much harder to kill.
- Heavily revised and improved pinning system. Allows sensibe things like titans not being pinned by some Gretchin, and makes units like knights much more valuable.
- Snapfire. Important in combination with alternating movement.
- split of the old command unit ability into HQ (can't be targetted) and Command (don't need orders, can move charge rate and still shoot).
- standardisation of lots of special rules into a set of ability descriptions with keywords.
Probably more but that's a start. However, even with all these improvements it still feels like classic Epic and is easy to pick up.