I was recently looking at this PrC. In my case, I was looking for something for a Bard-archer stlye. My assessment was that this PrC was not worth it for a bard.
What the Eldritch Knight gains (+1 BAB/level, extra feat, good fort saves) isn't worth what a bard has to give up (1 level of spellcasting, good dex & will saves, 6+skill points/level, song progression) in order to take it.
As a previous poster mentioned, it seems primarily tailored for a Fighter/Wizard or a Fighter/Sorcerer. IMHO, the easiest way to evaluate and compare it seems to be to keep spellcasting levels pretty close, so I'll try comparing a Fighter5/Wizard15 vs. a Fighter4/Wizard6/EK10.
Spellcaster level: 15 for both
Skills: Equal points, slightly different class choices
BAB: F/W has +12 BAB. EK version has +17 BAB
Saves: F/W has +9/+6/+10. EK has +13/+6/+9. Slight advantage toward EK, I guess.
Feats: F/W has 3 bonus fighter feats and 3 bonus wizard feats. EK has 4 bonus fighter feats and 1 bonus wizard feat. 1 less feat overall for the EK so this is a disadvantage.
Hit dice: F/W will have 5d10 + 15d4 (avg = 65 hp). EK version has 4d10 + 6d4 + 10d6 (avg = 72 hp). Advantage for EK.
So for that example, the EK version winds up with a significantly higher BAB (+5 is essentially an entire extra attack!), and somewhat better hit points, but trades a feat and some other minor mixing of saves and skills for it. Comparisons like this at other levels of fighter/wizard will no doubt vary quite a bit.
On the other hand, some would argue that a Fighter5/Wizard15 is already sub-optimal, so making comparisons with it aren't very valid. So make of it what you will...