Main changes are
You can reduce casting time to up 80% with -song spellcasting time/fast cap equipment. They've greatly increased the amount of song spellcasting time equipment available.
You can lower recast hugely with -song recast time equipment. You can lower debuffs from 24 seconds to 4 second recast with gear.
Songs last longer. You can get song+5 effect now and other equipment which increases song duration.
They've added Tier 2 Lullaby spells which sleep things for 60 second base. They are the same tier as tier 1 lullaby spells in sleep priority. So you can sleep something for 60 seconds with Lullaby 2 and then the lullaby can be overwrite with a sleep2.
MP recovery in now plentiful. There are two +1 Ballad equipment outside of G.horn. This means a non g.horn/daurdabla bard can ballad for 9mp/tic. Other jobs and buffs give lots of mp recovery so MP is rarely an issue. A g.horn/daurdabla bard can ballad for 21mp/tic.
Bard is still a good puller but the nature of exping has changed so we only pull situationally.
March is still awesome but with (the soon to be nerfed) embrava you can magical haste with just haste+embarava (for now).
Nightingale/Troubadour have had their effects improved so now 5/5 nightingale makes songs instant cast and 5/5 troubadour is like a 1min Elemental seal for all songs cast in that minute.
We have a new song called scherzo which lowers damage taken by high damage attacks (-45% damage for attacks that do more than 75% hp in a single hit) which makes things like EES/Mijin Gakure/Astral flow/Meteor (etc.) easily survivable. Summoner gets a similar effect and they stack with each other
There is a staff with all the HQ staves effect combined now so bards with g.horn and chatoyant staff can save a lot of inventory space. There are other new staffs which give more magic accuracy too.
There's too much to mention really.
The game has changed hugely since 2009 and I would recommend reading this:
http://wiki.bluegartr.com/bg/Returning_to_Vana%27diel