I'm writing recommendation to the colleague, could you please take a look if it is grammatically correct, as I have several concerns (highlighted). Also doesn't the text seems to be to 'heavy' for you?

Tom is one of the most experienced developers / technical consultants I was working with - he has showed high level expertise and quick understanding of the issues a number of times and suggested solutions in the same robust manner. He is also the person you can trust in critical situations - many times he has showed dedication to meet business expectations and to ensure business process continuity despite of the extra efforts required.

Thank you,