Yes. Serum 1 presets are compatible with Serum 2, so your existing Serum preset library should still work after upgrading.
Serum 2 was designed to support older Serum presets, meaning you can continue using your favourite sounds while taking advantage of the newer Serum 2 features, browser improvements and expanded creative tools.
However, compatibility does not work both ways. Serum 2 presets will not load in Serum 1, because they may use newer features and settings that do not exist in the original version.
If you are upgrading from Serum 1 to Serum 2, your old presets should remain useful — but any new packs created specifically for Serum 2 will require Serum 2 to open correctly.
Quantum Presets Serum 2 packs are built specifically for Serum 2, giving you modern preset design, improved workflow and sounds made for UKG, rave, jungle, dubstep and UK bass production.
Quick answer:
Serum 1 presets work in Serum 2. Serum 2 presets do not work in Serum 1.