I love this synthesizer, I really do... It has such a modern, "bombastic" sound, so punchy, so clear. That is exactly what modern producers need and use.
Oscillators are amazing, it is very hard to reproduce certain presets in other synthesizers to sound exactly the same, I find Spire always a touch bit better sounding than competing synths, just a little bit better.
Detune and unison section is nice, it sounds very sylenth-like, I find that not too many plugins can make that gritty and clear at the same time, low end saw bass, Spire (and Sylenth) does that perfectly.
Filters. They are good, plenty to choose from. I'm not a filter phreak, but they sound very good to my ear. I especially like "acido".
Effects section is quality as well. Shaper can sound really really mean, and reverb is an effect that could be justified as a standalone plugin, it's that good.
Other things I'm in love with are envelopes (they sound so snappy! I love it) and X-Comp module, which makes your sounds so clicky and modern sounding, helps them to stand out in the mix. It sounds especially good with envelopes set to short decay. I love this compressor.
Presets are top notch, they are "hit-ready" I would say, not like in other synths which may be packed with presets but only 1/5 of them is usable. Here you will find sounds which fit track perfectly and hence this synth is used by so many producers. It has great 3rd party soundbank support as well.
CPU usage... It used to suck, but now all is changed. I recently did a comparison with Dune and Hive. Hive, the so called "CPU efficient" synth was the most hoggy of all 3 and Dune was the most efficient. Spire was in the middle. It was quite surprising as I thought Hive will use the least amount of CPU processing power (as it is marketed) but well... Maybe it is just mine PC that does something in a different way. Spire's CPU usage is fine then.
In practice I didn't find any disadvantages, so I'm giving it a fair 10/10, as it is my fav synth and I can't quite find any other plugin with such features, such remarkable sound and overhelming amount of 3rd party presets.
I must admit it : this reverb is awesome! The best i've ever used, especially good on Trance genres like uplifting, ambient etc. I just love it, it can bring live to leads, move pads into othewordly space.
Its hard to believe, but insane sound quality of this plugin goes hand in hand with CPU-friendliness, i mean if I put Eos on any track, CPU meter in Ableton doesnt want to jump up to one percent... This is uncommon.
It has 3 algorithms and all 3 sounds gorgeus, but my absolutely favourite is hall, as I am trance producer.
I was looking for a good reverb for a long time, tried almost every available on the market, but srsly, only Eos (and maybe EasyVerb from PSP) is as good as I need it to be.
And the best part is price... 49 buck for that quality plugin (yeah its simple, but it sounds good and thats all that matters)... Must have.