Four necessary improvements are:
1) Handing of jump tables. This is very frequently used feature.
2) Script to handle offset tables (many of them are present),
so pressing two keys automatically changes all to offsets
(until it is proper address and stops as soon as it is not)
add xref and start analizing procedures.
3) Many parameters are passed by registers. If we could track them somehow and allow to quickly define this in function definition, so comments can be seen right after commands before call (ala pc.w32).
4) FR module have almost ready auto-comments. Is it desirable to make them work inside IDE (as gray auto-comments). As most people are quite new to this assembler.
If you have time and expirience working with IDA writing IDC scripts and/or plugins and modules, please, contact me.